No More Learning

The fourth difference between the heat of the
sun and fire is of great consequence; namely, that the sun, gradually,
and for a length of time, insinuates its effects, while those of fire
(urged by the impatience of man) are brought to a termination in a
shorter space of time. But if any one were to pay attention to the
tempering of fire, and reducing it to a more moderate and gentle degree
(which may be done in various ways), and then were to sprinkle and mix
a degree of humidity with it; and, above all, were to imitate the sun
in its inequality; and, lastly, were patiently to suffer some delay
(not such, however, as is proportioned to the effects of the sun,
but more than men usually admit of in those of fire), he would soon
banish the notion of any difference, and would attempt, or equal, or
perhaps sometimes surpass the effect of the sun, by the heat of fire.
A like instance of alliance is that of reviving butterflies, benumbed
and nearly dead from cold, by the gentle warmth of fire; so that fire
is no less able to revive animals than to ripen vegetables. We may
also mention the celebrated invention of Fracastorius, of applying a
pan considerably heated to the head in desperate cases of apoplexy,
which clearly expands the animal spirits, when compressed and almost
extinguished by the humors and obstructions of the brain, and excites
them to action, as the fire would operate on water or air, and in the
result produces life. Eggs are sometimes hatched by the heat of fire,
an exact imitation of animal heat; and there are many instances of the
like nature, so that no one can doubt that the heat of fire, in many
cases, can be modified till it resemble that of the heavenly bodies and
of animals.

Again, let the required natures be motion and rest. There appears to
be a settled classification, grounded on the deepest philosophy, that
natural bodies either revolve, move in a straight line, or stand still
and rest. For there is either motion without limit, or continuance
within a certain limit, or a translation toward a certain limit. The
eternal motion of revolution appears peculiar to the heavenly bodies,
rest to this our globe, and the other bodies (heavy and light, as they
are termed, that is to say, placed out of their natural position) are
borne in a straight line to masses or aggregates which resemble them,
the light toward the heaven, the heavy toward the earth; and all this
is very fine language.

But we have an instance of alliance in low comets, which revolve,
though far below the heavens; and the fiction of Aristotle, of the
comet being fixed to, or necessarily following some star, has been
long since exploded; not only because it is improbable in itself, but
from the evident fact of the discursive and irregular motion of comets
through various parts of the heavens. [125]

Another instance of alliance is that of the motion of air, which
appears to revolve from east to west within the tropics, where the
circles of revolution are the greatest.

The flow and ebb of the sea would perhaps be another instance, if the
water were once found to have a motion of revolution, though slow and
hardly perceptible, from east to west, subject, however, to a reaction
twice a day. If this be so, it is clear that the motion of revolution
is not confined to the celestial bodies, but is shared, also, by air
and water.

Again--the supposed peculiar disposition of light bodies to rise is
rather shaken; and here we may find an instance of alliance in a water
bubble. For if air be placed under water, it rises rapidly toward
the surface by that striking motion (as Democritus terms it) with
which the descending water strikes the air and raises it, not by any
struggle or effort of the air itself; and when it has reached the
surface of the water, it is prevented from ascending any further, by
the slight resistance it meets with in the water, which does not allow
an immediate separation of its parts, so that the tendency of the air
to rise must be very slight.

Again, let the required nature be weight. It is certainly a received
classification, that dense and solid bodies are borne toward the centre
of the earth, and rare and light bodies to the circumference of the
heavens, as their appropriate places. As far as relates to places
(though these things have much weight in the schools), the notion of
there being any determinate place is absurd and puerile. Philosophers
trifle, therefore, when they tell you, that if the earth were
perforated, heavy bodies would stop on their arrival at the centre.
This centre would indeed be an efficacious nothing, or mathematical
point, could it affect bodies or be sought by them, for a body is not
acted upon except by a body. [126] In fact, this tendency to ascend
and descend is either in the conformation of the moving body, or in
its harmony and sympathy with another body. But if any dense and solid
body be found, which does not, however, tend toward the earth, the
classification is at an end. Now, if we allow of Gilbert’s opinion,
that the magnetic power of the earth, in attracting heavy bodies, is
not extended beyond the limit of its peculiar virtue (which operates
always at a fixed distance and no further),[127] and this be proved by
some instance, such an instance will be one of alliance in our present
subject. The nearest approach to it is that of waterspouts, frequently
seen by persons navigating the Atlantic toward either of the Indies.
For the force and mass of the water suddenly effused by waterspouts,
appears to be so considerable, that the water must have been collected
previously, and have remained fixed where it was formed, until it was
afterward forced down by some violent cause, rather than made to fall
by the natural motion of gravity: so that it may be conjectured that
a dense and compact mass, at a great distance from the earth, may be
suspended as the earth itself is, and would not fall, unless forced
down. We do not, however, affirm this as certain. In the meanwhile,
both in this respect and many others, it will readily be seen how
deficient we are in natural history, since we are forced to have
recourse to suppositions for examples, instead of ascertained instances.

Again, let the required nature be the discursive power of the mind.
The classification of human reason and animal instinct appears to be
perfectly correct. Yet there are some instances of the actions of
brutes which seem to show that they, too, can syllogize. Thus it is
related, that a crow, which had nearly perished from thirst in a great
drought, saw some water in the hollow trunk of a tree, but as it was
too narrow for him to get into it, he continued to throw in pebbles,
which made the water rise till he could drink; and it afterward became
a proverb.

Again, let the required nature be vision. The classification
appears real and certain, which considers light as that which is
originally visible, and confers the power of seeing; and color, as
being secondarily visible, and not capable of being seen without
light, so as to appear a mere image or modification of light. Yet
there are instances of alliance in each respect; as in snow when in
great quantities, and in the flame of sulphur; the one being a color
originally and in itself light, the other a light verging toward
color. [128]

XXXVI. In the fourteenth rank of prerogative instances, we will place
the instances of the cross, borrowing our metaphor from the crosses
erected where two roads meet, to point out the different directions.
We are wont also to call them decisive and judicial instances, and in
some cases instances of the oracle and of command. Their nature is as
follows: When in investigating any nature the understanding is, as it
were, balanced, and uncertain to which of two or more natures the cause
of the required nature should be assigned, on account of the frequent
and usual concurrence of several natures, the instances of the cross
show that the union of one nature with the required nature is firm
and indissoluble, while that of the other is unsteady and separable;
by which means the question is decided, and the first is received as
the cause, while the other is dismissed and rejected. Such instances,
therefore, afford great light, and are of great weight, so that the
course of interpretation sometimes terminates, and is completed in
them. Sometimes, however, they are found among the instances already
observed, but they are generally new, being expressly and purposely
sought for and applied, and brought to light only by attentive and
active diligence.

For example: let the required nature be the flow and ebb of the sea,
which is repeated twice a day, at intervals of six hours between each
advance and retreat, with some little difference, agreeing with the
motion of the moon. We have here the following crossways:

This motion must be occasioned either by the advancing and the retiring
of the sea, like water shaken in a basin, which leaves one side while
it washes the other; or by the rising of the sea from the bottom,
and its again subsiding, like boiling water. But a doubt arises, to
which of these causes we should assign the flow and ebb. If the first
assertion be admitted, it follows, that when there is a flood on
one side, there must at the same time be an ebb on another, and the
question therefore is reduced to this. Now Acosta, and some others,
after a diligent inquiry, have observed that the flood tide takes place
on the coast of Florida, and the opposite coasts of Spain and Africa,
at the same time, as does also the ebb; and that there is not, on the
contrary, a flood tide at Florida when there is an ebb on the coasts
of Spain and Africa. Yet if one consider the subject attentively,
this does not prove the necessity of a rising motion, nor refute the
notion of a progressive motion. For the motion may be progressive, and
yet inundate the opposite shores of a channel at the same time; as if
the waters be forced and driven together from some other quarter, for
instance, which takes place in rivers, for they flow and ebb toward
each bank at the same time, yet their motion is clearly progressive,
being that of the waters from the sea entering their mouths. So it may
happen, that the waters coming in a vast body from the eastern Indian
Ocean are driven together, and forced into the channel of the Atlantic,
and therefore inundate both coasts at once. We must inquire, therefore,
if there be any other channel by which the waters can at the same time
sink and ebb; and the Southern Ocean at once suggests itself, which is
not less than the Atlantic, but rather broader and more extensive than
is requisite for this effect.

We at length arrive, then, at an instance of the cross, which is this.
If it be positively discovered, that when the flood sets in toward
the opposite coasts of Florida and Spain in the Atlantic, there is at
the same time a flood tide on the coasts of Peru and the back part
of China, in the Southern Ocean, then assuredly, from this decisive
instance, we must reject the assertion, that the flood and ebb of the
sea, about which we inquire, takes place by progressive motion; for
no other sea or place is left where there can be an ebb. But this may
most easily be learned, by inquiring of the inhabitants of Panama and
Lima (where the two oceans are separated by a narrow isthmus), whether
the flood and ebb takes place on the opposite sides of the isthmus
at the same time, or the reverse. This decision or rejection appears
certain, if it be granted that the earth is fixed; but if the earth
revolves, it may perhaps happen, that from the unequal revolution (as
regards velocity) of the earth and the waters of the sea, there may
be a violent forcing of the waters into a mass, forming the flood,
and a subsequent relaxation of them (when they can no longer bear the
accumulation), forming the ebb. A separate inquiry must be made into
this. Even with this hypothesis, however, it remains equally true, that
there must be an ebb somewhere, at the same time that there is a flood
in another quarter.

Again, let the required nature be the latter of the two motions we
have supposed; namely, that of a rising and subsiding motion, if it
should happen that upon diligent examination the progressive motion
be rejected. We have, then, three ways before us, with regard to this
nature. The motion, by which the waters raise themselves, and again
fall back, in the floods and ebbs, without the addition of any other
water rolled toward them, must take place in one of the three following
ways: Either the supply of water emanates from the interior of the
earth, and returns back again; or there is really no greater quantity
of water, but the same water (without any augmentation of its quantity)
is extended or rarefied, so as to occupy a greater space and dimension,
and again contracts itself; or there is neither an additional supply
nor any extension, but the same waters (with regard to quantity,
density, or rarity) raise themselves and fall from sympathy, by some
magnetic power attracting and calling them up, as it were, from
above. Let us then (passing over the first two motions) reduce the
investigation to the last, and inquire if there be any such elevation
of the water by sympathy or a magnetic force; and it is evident, in the
first place, that the whole mass of water being placed in the trench
or cavity of the sea, cannot be raised at once, because there would
not be enough to cover the bottom, so that if there be any tendency of
this kind in the water to raise itself, yet it would be interrupted
and checked by the cohesion of things, or (as the common expression
is) that there may be no vacuum. The water, therefore, must rise on
one side, and for that reason be diminished and ebb on another. But it
will again necessarily follow that the magnetic power not being able to
operate on the whole, operates most intensely on the centre, so as to
raise the waters there, which, when thus raised successively, desert
and abandon the sides. [129]

We at length arrive, then, at an instance of the cross, which is this:
if it be found that during the ebb the surface of the waters at sea
is more curved and round, from the waters rising in the middle, and
sinking at the sides or coast, and if, during a flood, it be more even
and level, from the waters returning to their former position, then
assuredly, by this decisive instance, the raising of them by a magnetic
force can be admitted; if otherwise, it must be entirely rejected.
It is not difficult to make the experiment (by sounding in straits),
whether the sea be deeper toward the middle in ebbs, than in floods.
But it must be observed, if this be the case, that (contrary to common
opinion) the waters rise in ebbs, and only return to their former
position in floods, so as to bathe and inundate the coast.

Again, let the required nature be the spontaneous motion of revolution,
and particularly, whether the diurnal motion, by which the sun and
stars appear to us to rise and set, be a real motion of revolution in
the heavenly bodies, or only apparent in them, and real in the earth.
There may be an instance of the cross of the following nature. If there
be discovered any motion in the ocean from east to west, though very
languid and weak, and if the same motion be discovered rather more
swift in the air (particularly within the tropics, where it is more
perceptible from the circles being greater). If it be discovered also
in the low comets, and be already quick and powerful in them; if it
be found also in the planets, but so tempered and regulated as to be
slower in those nearest the earth, and quicker in those at the greatest
distance, being quickest of all in the heavens, then the diurnal motion
should certainly be considered as real in the heavens, and that of the
earth must be rejected; for it will be evident that the motion from
east to west is part of the system of the world and universal; since it
is most rapid in the height of the heavens, and gradually grows weaker,
till it stops and is extinguished in rest at the earth.

Again, let the required nature be that other motion of revolution,
so celebrated among astronomers, which is contrary to the diurnal,
namely, from west to east--and which the ancient astronomers assign
to the planets, and even to the starry sphere, but Copernicus and his
followers to the earth also--and let it be examined whether any such
motion be found in nature, or it be rather a fiction and hypothesis
for abridging and facilitating calculation, and for promoting that
fine notion of effecting the heavenly motions by perfect circles; for
there is nothing which proves such a motion in heavenly objects to be
true and real, either in a planet’s not returning in its diurnal motion
to the same point of the starry sphere, or in the pole of the zodiac
being different from that of the world, which two circumstances have
occasioned this notion. For the first phenomenon is well accounted for
by the spheres overtaking or falling behind each other, and the second
by spiral lines; so that the inaccuracy of the return and declination
to the tropics may be rather modifications of the one diurnal motion
than contrary motions, or about different poles. And it is most
certain, if we consider ourselves for a moment as part of the vulgar
(setting aside the fictions of astronomers and the school, who are
wont undeservedly to attack the senses in many respects, and to affect
obscurity), that the apparent motion is such as we have said, a model
of which we have sometimes caused to be represented by wires in a sort
of a machine.

We may take the following instances of the cross upon this subject. If
it be found in any history worthy of credit, that there has existed any
comet, high or low, which has not revolved in manifest harmony (however
irregularly) with the diurnal motion, then we may decide so far as to
allow such a motion to be possible in nature. But if nothing of the
sort be found, it must be suspected, and recourse must be had to other
instances of the cross.

Again, let the required nature be weight or gravity. Heavy and
ponderous bodies must, either of their own nature, tend toward the
centre of the earth by their peculiar formation, or must be attracted
and hurried by the corporeal mass of the earth itself, as being an
assemblage of similar bodies, and be drawn to it by sympathy. But if
the latter be the cause, it follows that the nearer bodies approach to
the earth, the more powerfully and rapidly they must be borne toward
it, and the further they are distant, the more faintly and slowly (as
is the case in magnetic attractions), and that this must happen within
a given distance; so that if they be separated at such a distance from
the earth that the power of the earth cannot act upon them, they will
remain suspended like the earth, and not fall at all. [130]

The following instance of the cross may be adopted. Take a clock moved
by leaden weights,[131] and another by a spring, and let them be set
well together, so that one be neither quicker nor slower than the
other; then let the clock moved by weights be placed on the top of
a very high church, and the other be kept below, and let it be well
observed, if the former move slower than it did, from the diminished
power of the weights. Let the same experiment be made at the bottom
of mines worked to a considerable depth, in order to see whether the
clock move more quickly from the increased power of the weights. But
if this power be found to diminish at a height, and to increase in
subterraneous places, the attraction of the corporeal mass of the earth
may be taken as the cause of weight.

Again, let the required nature be the polarity of the steel needle when
touched with the magnet. We have these two ways with regard to this
nature--Either the touch of the magnet must communicate polarity to
the steel toward the north and south, or else it may only excite and
prepare it, while the actual motion is occasioned by the presence of
the earth, which Gilbert considers to be the case, and endeavors to
prove with so much labor. The particulars he has inquired into with
such ingenious zeal amount to this--1. An iron bolt placed for a long
time toward the north and south acquires polarity from this habit,
without the touch of the magnet, as if the earth itself operating
but weakly from its distance (for the surface or outer crust of the
earth does not, in his opinion, possess the magnetic power), yet, by
long continued motion, could supply the place of the magnet, excite
the iron, and convert and change it when excited. 2. Iron, at a red
or white heat, when quenched in a direction parallel to the north
and south, also acquires polarity without the touch of the magnet, as
if the parts of iron being put in motion by ignition, and afterward
recovering themselves, were, at the moment of being quenched, more
susceptible and sensitive of the power emanating from the earth, than
at other times, and therefore as it were excited. But these points,
though well observed, do not completely prove his assertion.

An instance of the cross on this point might be as follows: Let a small
magnetic globe be taken, and its poles marked, and placed toward the
east and west, not toward the north and south, and let it continue
thus. Then let an untouched needle be placed over it, and suffered
to remain so for six or seven days. Now, the needle (for this is not
disputed), while it remains over the magnet, will leave the poles of
the world and turn to those of the magnet, and therefore, as long as it
remains in the above position, will turn to the east and west. But if
the needle, when removed from the magnet and placed upon a pivot, be
found immediately to turn to the north and south, or even by degrees
to return thither, then the presence of the earth must be considered
as the cause, but if it remains turned as at first, toward the east
and west, or lose its polarity, then that cause must be suspected, and
further inquiry made.

Again, let the required nature be the corporeal substance of the
moon, whether it be rare, fiery, and aërial (as most of the ancient
philosophers have thought), or solid and dense (as Gilbert and many
of the moderns, with some of the ancients, hold). [132] The reasons
for this latter opinion are grounded chiefly upon this, that the
moon reflects the sun’s rays, and that light does not appear capable
of being reflected except by solids. The instances of the cross will
therefore (if any) be such as to exhibit reflection by a rare body,
such as flame, if it be but sufficiently dense. Now, certainly, one
of the reasons of twilight is the reflection[133] of the rays of the
sun by the upper part of the atmosphere. We see the sun’s rays also
reflected on fine evenings by streaks of moist clouds, with a splendor
not less, but perhaps more bright and glorious than that reflected
from the body of the moon, and yet it is not clear that those clouds
have formed into a dense body of water. We see, also, that the dark
air behind the windows at night reflects the light of a candle in the
same manner as a dense body would do. [134] The experiment should also
be made of causing the sun’s rays to fall through a hole upon some dark
and bluish flame. The unconfined rays of the sun, when falling on faint
flames, do certainly appear to deaden them, and render them more like
white smoke than flames. These are the only instances which occur at
present of the nature of those of the cross, and better perhaps can
be found. But it must always be observed that reflection is not to
be expected from flame, unless it be of some depth, for otherwise it
becomes nearly transparent. This at least may be considered certain,
that light is always either received and transmitted or reflected by an
even surface.

Again, let the required nature be the motion of projectiles (such
as darts, arrows, and balls) through the air. The school, in its
usual manner, treats this very carelessly, considering it enough to
distinguish it by the name of violent motion, from that which they
term natural, and as far as regards the first percussion or impulse,
satisfies itself by its axiom, that two bodies cannot exist in one
place, or there would be a penetration of dimensions. With regard to
this nature we have these two crossways--The motion must arise either
from the air carrying the projected body, and collecting behind it,
like a stream behind boats, or the wind behind straws; or from the
parts of the body itself not supporting the impression, but pushing
themselves forward in succession to ease it. Fracastorius, and nearly
all those who have entered into any refined inquiry upon the subject,
adopt the first. Nor can it be doubted that the air has some effect,
yet the other motion is without doubt real, as is clear from a vast
number of experiments. Among others we may take this instance of the
cross, namely, that a thin plate or wire of iron rather stiff, or even
a reed or pen split in two, when drawn up and bent between the finger
and thumb, will leap forward; for it is clear that this cannot be
attributed to the air’s being collected behind the body, because the
source of motion is in the centre of the plate or pen, and not in its
extremities.

Again, let the required nature be the rapid and powerful motion of the
explosion of gunpowder, by which such vast masses are upheaved, and
such weights discharged as we observe in large mines and mortars, there
are two crossways before us with regard to this nature. This motion
is excited either by the mere effort of the body expanding itself when
inflamed, or by the assisting effort of the crude spirit, which escapes
rapidly from fire, and bursts violently from the surrounding flame as
from a prison. The school, however, and common opinion only consider
the first effort; for men think that they are great philosophers when
they assert that flame, from the form of the element, is endowed with
a kind of necessity of occupying a greater space than the same body
had occupied when in the form of powder, and that thence proceeds the
motion in question. In the meantime they do not observe, that although
this may be true, on the supposition of flame being generated, yet the
generation may be impeded by a weight of sufficient force to compress
and suffocate it, so that no such necessity exists as they assert. They
are right, indeed, in imagining that the expansion and the consequent
emission or removal of the opposing body, is necessary if flame be once
generated, but such a necessity is avoided if the solid opposing mass
suppress the flame before it be generated; and we in fact see that
flame, especially at the moment of its generation, is mild and gentle,
and requires a hollow space where it can play and try its force. The
great violence of the effect, therefore, cannot be attributed to this
cause; but the truth is, that the generation of these exploding flames
and fiery blasts arises from the conflict of two bodies of a decidedly
opposite nature--the one very inflammable, as is the sulphur, the
other having an antipathy to flame, namely, the crude spirit of the
nitre; so that an extraordinary conflict takes place while the sulphur
is becoming inflamed as far as it can (for the third body, the willow
charcoal, merely incorporates and conveniently unites the two others),
and the spirit of nitre is escaping, as far also as it can, and at
the same time expanding itself (for air, and all crude substances,
and water are expanded by heat), fanning thus, in every direction,
the flame of the sulphur by its escape and violence, just as if by
invisible bellows.

Two kinds of instances of the cross might here be used--the one of
very inflammable substances, such as sulphur and camphor, naphtha and
the like, and their compounds, which take fire more readily and easily
than gunpowder if left to themselves (and this shows that the effort
to catch fire does not of itself produce such a prodigious effect);
the other of substances which avoid and repel flame, such as all
salts; for we see that when they are cast into the fire, the aqueous
spirit escapes with a crackling noise before flame is produced, which
also happens in a less degree in stiff leaves, from the escape of
the aqueous part before the oily part has caught fire. This is more
particularly observed in quicksilver, which is not improperly called
mineral water, and which, without any inflammation, nearly equals the
force of gunpowder by simple explosion and expansion, and is said, when
mixed with gunpowder, to increase its force.

Again, let the required nature be the transitory nature of flame and
its momentaneous extinction; for to us the nature of flame does not
appear to be fixed or settled, but to be generated from moment to
moment, and to be every instant extinguished; it being clear that
those flames which continue and last, do not owe their continuance to
the same mass of flame, but to a continued succession of new flame
regularly generated, and that the same identical flame does not
continue. This is easily shown by removing the food or source of the
flame, when it at once goes out. We have the two following crossways
with regard to this nature:

This momentary nature either arises from the cessation of the cause
which first produced it, as in light, sounds, and violent motions,
as they are termed, or flame may be capable, by its own nature, of
duration, but is subjected to some violence from the contrary natures
which surround it, and is destroyed.

We may therefore adopt the following instance of the cross. We see
to what a height the flames rise in great conflagrations; for as the
base of the flame becomes more extensive, its vertex is more lofty.
It appears, then, that the commencement of the extinction takes place
at the sides, where the flame is compressed by the air, and is ill
at ease; but the centre of the flame, which is untouched by the air
and surrounded by flame, continues the same, and is not extinguished
until compressed by degrees by the air attacking it from the sides.
All flame, therefore, is pyramidal, having its base near the source,
and its vertex pointed from its being resisted by the air, and not
supplied from the source. On the contrary, the smoke, which is narrow
at the base, expands in its ascent, and resembles an inverted pyramid,
because the air admits the smoke, but compresses the flame; for let
no one dream that the lighted flame is air, since they are clearly
heterogeneous.

The instance of the cross will be more accurate, if the experiment can
be made by flames of different colors. Take, therefore, a small metal
sconce, and place a lighted taper in it, then put it in a basin, and
pour a small quantity of spirits of wine round the sconce, so as not to
reach its edge, and light the spirit. Now the flame of the spirit will
be blue, and that of the taper yellow; observe, therefore, whether the
latter (which can easily be distinguished from the former by its color,
for flames do not mix immediately, as liquids do) continue pyramidal,
or tend more to a globular figure, since there is nothing to destroy or
compress it. If the latter result be observed, it must be considered
as settled, that flame continues positively the same, while inclosed
within another flame, and not exposed to the resisting force of the air.

Let this suffice for the instances of the cross. We have dwelt the
longer upon them in order gradually to teach and accustom mankind to
judge of nature by these instances, and enlightening experiments, and
not by probable reasons. [135]

XXXVII. We will treat of the instances of divorce as the fifteenth of
our prerogative instances. They indicate the separation of natures of
the most common occurrence. They differ, however, from those subjoined
to the accompanying instances; for the instances of divorce point out
the separation of a particular nature from some concrete substance with
which it is usually found in conjunction, while the hostile instances
point out the total separation of one nature from another. They differ,
also, from the instances of the cross, because they decide nothing, but
only inform us that the one nature is capable of being separated from
the other. They are of use in exposing false forms, and dissipating
hasty theories derived from obvious facts; so that they add ballast and
weight, as it were, to the understanding.

For instance, let the acquired natures be those four which Telesius
terms associates, and of the same family, namely, heat, light, rarity,
and mobility, or promptitude to motion; yet many instances of divorce
can be discovered between them. Air is rare and easily moved, but
neither hot nor light; the moon is light but not hot; boiling water is
warm but not light; the motion of the needle in the compass is swift
and active, and yet its substance is cold, dense, and opaque; and there
are many similar examples.

Again, let the required natures be corporeal nature and natural action.
The latter appears incapable of subsisting without some body, yet may
we, perhaps, even here find an instance of divorce, as in the magnetic
motion, which draws the iron to the magnet, and heavy bodies to the
globe of the earth; to which we may add other actions which operate at
a distance. For such action takes place in time, by distinct moments,
not in an instant; and in space, by regular degrees and distances.
There is, therefore, some one moment of time and some interval of
space, in which the power or action is suspended between the two bodies
creating the motion. Our consideration, then, is reduced to this,
whether the bodies which are the extremes of motion prepare or alter
the intermediate bodies, so that the power advances from one extreme
to the other by succession and actual contact, and in the meantime
exists in some intermediate body; or whether there exists in reality
nothing but the bodies, the power, and the space? In the case of the
rays of light, sounds, and heat, and some other objects which operate
at a distance, it is indeed probable that the intermediate bodies
are prepared and altered, the more so because a qualified medium is
required for their operation. But the magnetic or attractive power
admits of an indifferent medium, and it is not impeded in any. But
if that power or action is independent of the intermediate body, it
follows that it is a natural power or action existing in a certain time
and space without any body, since it exists neither in the extreme nor
in the intermediate bodies. Hence the magnetic action may be taken as
an instance of divorce of corporeal nature and natural action; to which
we may add, as a corollary and an advantage not to be neglected, that
it may be taken as a proof of essence and substance being separate and
incorporeal, even by those who philosophize according to the senses.
For if natural power and action emanating from a body can exist at any
time and place entirely without any body, it is nearly a proof that
it can also emanate originally from an incorporeal substance; for a
corporeal nature appears to be no less necessary for supporting and
conveying, than for exciting or generating natural action.

XXXVIII. Next follow five classes of instances which we are wont to
call by the general term of instances of the lamp, or of immediate
information. They are such as assist the senses; for since every
interpretation of nature sets out from the senses, and leads, by a
regular fixed and well-established road, from the perceptions of
the senses to those of the understanding (which are true notions
and axioms), it necessarily follows, that in proportion as the
representatives or ministerings of the senses are more abundant and
accurate, everything else must be more easy and successful.

The first of these five sets of instances of the lamp, strengthen,
enlarge, and correct the immediate operations of the senses; the second
reduce to the sphere of the senses such matters as are beyond it; the
third indicate the continued process or series of such things and
motions, as for the most part are only observed in their termination,
or in periods; the fourth supply the absolute wants of the senses; the
fifth excite their attention and observation, and at the same time
limit the subtilty of things. We will now proceed to speak of them
singly.

XXXIX. In the sixteenth rank, then, of prerogative instances, we will
place the instances of the door or gate, by which name we designate
such as assist the immediate action of the senses. It is obvious,
that sight holds the first rank among the senses, with regard to
information, for which reason we must seek principally helps for that
sense. These helps appear to be threefold, either to enable it to
perceive objects not naturally seen, or to see them from a greater
distance, or to see them more accurately and distinctly.

We have an example of the first (not to speak of spectacles and the
like, which only correct and remove the infirmity of a deficient
sight, and therefore give no further information) in the lately
invented microscopes, which exhibit the latent and invisible minutiæ
of substances, and their hidden formation and motion, by wonderfully
increasing their apparent magnitude. By their assistance we behold
with astonishment the accurate form and outline of a flea, moss, and
animalculæ, as well as their previously invisible color and motion.
It is said, also, that an apparently straight line, drawn with a
pen or pencil, is discovered by such a microscope to be very uneven
and curved, because neither the motion of the hand, when assisted
by a ruler, nor the impression of ink or color, are really regular,
although the irregularities are so minute as not to be perceptible
without the assistance of the microscope. Men have (as is usual in
new and wonderful discoveries) added a superstitious remark, that
the microscope sheds a lustre on the works of nature, and dishonor
on those of art, which only means that the tissue of nature is much
more delicate than that of art. For the microscope is only of use for
minute objects, and Democritus, perhaps, if he had seen it, would have
exulted in the thought of a means being discovered for seeing his atom,
which he affirmed to be entirely invisible. But the inadequacy of these
microscopes, for the observation of any but the most minute bodies, and
even of those if parts of a larger body, destroys their utility; for
if the invention could be extended to greater bodies, or the minute
parts of greater bodies, so that a piece of cloth would appear like a
net, and the latent minutiæ and irregularities of gems, liquids, urine,
blood, wounds, and many other things could be rendered visible, the
greatest advantage would, without doubt, be derived.

We have an instance of the second kind in the telescope, discovered
by the wonderful exertions of Galileo; by the assistance of which a
nearer intercourse may be opened (as by boats or vessels) between
ourselves and the heavenly objects. For by its aid we are assured
that the Milky Way is but a knot or constellation of small stars,
clearly defined and separate, which the ancients only conjectured to
be the case; whence it appears to be capable of demonstration, that
the spaces of the planetary orbits (as they are termed) are not quite
destitute of other stars, but that the heaven begins to glitter with
stars before we arrive at the starry sphere, although they may be too
small to be visible without the telescope. By the telescope, also, we
can behold the revolutions of smaller stars round Jupiter, whence it
may be conjectured that there are several centres of motion among the
stars. By its assistance, also, the irregularity of light and shade on
the moon’s surface is more clearly observed and determined, so as to
allow of a sort of selenography. [136] By the telescope we see the spots
in the sun, and other similar phenomena; all of which are most noble
discoveries, as far as credit can be safely given to demonstrations
of this nature, which are on this account very suspicious, namely,
that experiment stops at these few, and nothing further has yet
been discovered by the same method, among objects equally worthy of
consideration.

We have instances of the third kind in measuring-rods, astrolabes,
and the like, which do not enlarge, but correct and guide the sight.
If there be other instances which assist the other senses in their
immediate and individual action, yet if they add nothing further to
their information they are not apposite to our present purpose, and we
have therefore said nothing of them.

XL. In the seventeenth rank of prerogative instances we will place
citing instances (to borrow a term from the tribunals), because they
cite those things to appear, which have not yet appeared. We are wont
also to call them invoking instances, and their property is that of
reducing to the sphere of the senses objects which do not immediately
fall within it.

Objects escape the senses either from their distance, or the
intervention of other bodies, or because they are not calculated
to make an impression upon the senses, or because they are not in
sufficient quantity to strike the senses, or because there is not
sufficient time for their acting upon the senses, or because the
impression is too violent, or because the senses are previously filled
and possessed by the object, so as to leave no room for any new motion.
These remarks apply principally to sight, and next to touch, which two
senses act extensively in giving information, and that too upon general
objects, while the remaining three inform us only, as it were, by their
immediate action, and as to specific objects.

There can be no reduction to the sphere of the senses in the first
case, unless in the place of the object, which cannot be perceived
on account of the distance, there be added or substituted some other
object, which can excite and strike the sense from a greater distance,
as in the communication of intelligence by fires, bells, and the like.

In the second case we effect this reduction by rendering those things
which are concealed by the interposition of other bodies, and which
cannot easily be laid open, evident to the senses by means of that
which lies at the surface, or proceeds from the interior; thus the
state of the body is judged of by the pulse, urine, etc.

The third and fourth cases apply to many subjects, and the reduction
to the sphere of the senses must be obtained from every quarter in the
investigation of things. There are many examples. It is obvious that
air, and spirit, and the like, whose whole substance is extremely rare
and delicate, can neither be seen nor touched--a reduction, therefore,
to the senses becomes necessary in every investigation relating to such
bodies.

Let the required nature, therefore, be the action and motion of the
spirit inclosed in tangible bodies; for every tangible body with which
we are acquainted contains an invisible and intangible spirit, over
which it is drawn, and which it seems to clothe. This spirit being
emitted from a tangible substance, leaves the body contracted and dry;
when retained, it softens and melts it; when neither wholly emitted nor
retained, it models it, endows it with limbs, assimilates, manifests,
organizes it, and the like. All these points are reduced to the sphere
of the senses by manifest effects.

For in every tangible and inanimate body the inclosed spirit at first
increases, and as it were feeds on the tangible parts which are most
open and prepared for it; and when it has digested and modified them,
and turned them into spirit, it escapes with them. This formation and
increase of spirit is rendered sensible by the diminution of weight;
for in every desiccation something is lost in quantity, not only of
the spirit previously existing in the body, but of the body itself,
which was previously tangible, and has been recently changed, for the
spirit itself has no weight. The departure or emission of spirit is
rendered sensible in the rust of metals, and other putrefactions of a
like nature, which stop before they arrive at the rudiments of life,
which belong to the third species of process. [137] In compact bodies
the spirit does not find pores and passages for its escape, and is
therefore obliged to force out, and drive before it, the tangible parts
also, which consequently protrude, whence arises rust and the like. The
contraction of the tangible parts, occasioned by the emission of part
of the spirit (whence arises desiccation), is rendered sensible by the
increased hardness of the substance, and still more by the fissures,
contractions, shrivelling, and folds of the bodies thus produced. For
the parts of wood split and contract, skins become shrivelled, and not
only that, but, if the spirit be emitted suddenly by the heat of the
fire, become so hastily contracted as to twist and roll themselves up.

On the contrary, when the spirit is retained, and yet expanded and
excited by heat or the like (which happens in solid and tenacious
bodies), then the bodies are softened, as in hot iron; or flow, as in
metals; or melt, as in gums, wax, and the like. The contrary effects
of heat, therefore (hardening some substances and melting others), are
easily reconciled,[138] because the spirit is emitted in the former,
and agitated and retained in the latter; the latter action is that of
heat and the spirit, the former that of the tangible parts themselves,
after the spirit’s emission.

But when the spirit is neither entirely retained nor emitted, but
only strives and exercises itself, within its limits, and meets with
tangible parts, which obey and readily follow it wherever it leads
them, then follows the formation of an organic body, and of limbs, and
the other vital actions of vegetables and animals. These are rendered
sensible chiefly by diligent observation of the first beginnings, and
rudiments or effects of life in animalculæ sprung from putrefaction, as
in the eggs of ants, worms, mosses, frogs after rain, etc. Both a mild
heat and a pliant substance, however, are necessary for the production
of life, in order that the spirit may neither hastily escape, nor be
restrained by the obstinacy of the parts, so as not to be able to bend
and model them like wax.

Again, the difference of spirit which is important and of effect
in many points (as unconnected spirit, branching spirit, branching
and cellular spirit, the first of which is that of all inanimate
substances, the second of vegetables, and the third of animals), is
placed, as it were, before the eyes by many reducing instances.

Again, it is clear that the more refined tissue and conformation of
things (though forming the whole body of visible or tangible objects)
are neither visible nor tangible. Our information, therefore, must
here also be derived from reduction to the sphere of the senses. But
the most radical and primary difference of formation depends on the
abundance or scarcity of matter within the same space or dimensions.
For the other formations which regard the dissimilarity of the parts
contained in the same body, and their collocation and position, are
secondary in comparison with the former.
Let the required nature then be the expansion or coherence of matter in
different bodies, or the quantity of matter relative to the dimensions
of each. For there is nothing in nature more true than the twofold
proposition--that nothing proceeds from nothing and that nothing is
reduced to nothing, but that the quantum, or sum total of matter, is
constant, and is neither increased nor diminished. Nor is it less true,
that out of this given quantity of matter, there is a greater or less
quantity, contained within the same space or dimensions according to
the difference of bodies; as, for instance, water contains more than
air. So that if any one were to assert that a given content of water
can be changed into an equal content of air, it is the same as if he
were to assert that something can be reduced into nothing. On the
contrary, if any one were to assert that a given content of air can be
changed into an equal content of water, it is the same as if he were
to assert that something can proceed from nothing. From this abundance
or scarcity of matter are properly derived the notions of density and
rarity, which are taken in various and promiscuous senses.

This third assertion may be considered as being also sufficiently
certain; namely, that the greater or less quantity of matter in this or
that body, may, by comparison, be reduced to calculation, and exact, or
nearly exact, proportion. Thus, if one should say that there is such
an accumulation of matter in a given quantity of gold, that it would
require twenty-one times the quantity in dimension of spirits of wine,
to make up the same quantity of matter, it would not be far from the
truth.

The accumulation of matter, however, and its relative quantity, are
rendered sensible by weight; for weight is proportionate to the
quantity of matter, as regards the parts of a tangible substance, but
spirit and its quantity of matter are not to be computed by weight,
which spirit rather diminishes than augments.

We have made a tolerably accurate table of weight, in which we have
selected the weights and size of all the metals, the principal
minerals, stones, liquids, oils, and many other natural and artificial
bodies: a very useful proceeding both as regards theory and practice,
and which is capable of revealing many unexpected results. Nor is this
of little consequence, that it serves to demonstrate that the whole
range of the variety of tangible bodies with which we are acquainted
(we mean tolerably close, and not spongy, hollow bodies, which are for
a considerable part filled with air), does not exceed the ratio of one
to twenty-one. So limited is nature, or at least that part of it to
which we are most habituated.

We have also thought it deserving our industry, to try if we could
arrive at the ratio of intangible or pneumatic bodies to tangible
bodies, which we attempted by the following contrivance. We took a
vial capable of containing about an ounce, using a small vessel in
order to effect the subsequent evaporation with less heat. We filled
this vial, almost to the neck, with spirits of wine, selecting it as
the tangible body which, by our table, was the rarest, and contained a
less quantity of matter in a given space than all other tangible bodies
which are compact and not hollow. Then we noted exactly the weight
of the liquid and vial. We next took a bladder, containing about two
pints, and squeezed all the air out of it, as completely as possible,
and until the sides of the bladder met. We first, however, rubbed the
bladder gently with oil, so as to make it air-tight, by closing its
pores with the oil. We tied the bladder tightly round the mouth of the
vial, which we had inserted in it, and with a piece of waxed thread
to make it fit better and more tightly, and then placed the vial on
some hot coals in a brazier. The vapor or steam of the spirit, dilated
and become aëriform by the heat, gradually swelled out the bladder,
and stretched it in every direction like a sail. As soon as that was
accomplished, we removed the vial from the fire and placed it on a
carpet, that it might not be cracked by the cold; we also pricked the
bladder immediately, that the steam might not return to a liquid state
by the cessation of heat, and confound the proportions. We then removed
the bladder, and again took the weight of the spirit which remained;
and so calculated the quantity which had been converted into vapor, or
an aëriform shape, and then examined how much space had been occupied
by the body in its form of spirits of wine in the vial, and how much,
on the other hand, had been occupied by it in its aëriform shape in the
bladder, and subtracted the results; from which it was clear that the
body, thus converted and changed, acquired an expansion of one hundred
times beyond its former bulk.

Again, let the required nature be heat or cold, of such a degree as
not to be sensible from its weakness. They are rendered sensible by
the thermometer, as we described it above;[139] for the cold and heat
are not actually perceived by the touch, but heat expands and cold
contracts the air. Nor, again, is that expansion or contraction of the
air in itself visible, but the air when expanded depresses the water,
and when contracted raises it, which is the first reduction to sight.

Again, let the required nature be the mixture of bodies; namely,
how much aqueous, oleaginous or spirituous, ashy or salt parts they
contain; or, as a particular example, how much butter, cheese, and whey
there is in milk, and the like. These things are rendered sensible by
artificial and skilful separations in tangible substances; and the
nature of the spirit in them, though not immediately perceptible, is
nevertheless discovered by the various motions and efforts of bodies.
And, indeed, in this branch men have labored hard in distillations
and artificial separations, but with little more success than in
their other experiments now in use; their methods being mere guesses
and blind attempts, and more industrious than intelligent; and what
is worst of all, without any imitation or rivalry of nature, but
rather by violent heats and too energetic agents, to the destruction
of any delicate conformation, in which principally consist the
hidden virtues and sympathies. Nor do men in these separations ever
attend to or observe what we have before pointed out; namely, that
in attacking bodies by fire, or other methods, many qualities are
superinduced by the fire itself, and the other bodies used to effect
the separation, which were not originally in the compound. Hence arise
most extraordinary fallacies; for the mass of vapor which is emitted
from water by fire, for instance, did not exist as vapor or air in the
water, but is chiefly created by the expansion of the water by the heat
of the fire.

So, in general, all delicate experiments on natural or artificial
bodies, by which the genuine are distinguished from the adulterated,
and the better from the more common, should be referred to this
division; for they bring that which is not the object of the senses
within their sphere. They are therefore to be everywhere diligently
sought after.

With regard to the fifth cause of objects escaping our senses, it is
clear that the action of the sense takes place by motion, and this
motion is time. If, therefore, the motion of any body be either so slow
or so swift as not to be proportioned to the necessary momentum which
operates on the senses, the object is not perceived at all; as in the
motion of the hour hand, and that, again, of a musket-ball. The motion
which is imperceptible by the senses from its slowness, is readily and
usually rendered sensible by the accumulation of motion; that which is
imperceptible from its velocity, has not as yet been well measured; it
is necessary, however, that this should be done in some cases, with a
view to a proper investigation of nature.

The sixth case, where the sense is impeded by the power of the object,
admits of a reduction to the sensible sphere, either by removing the
object to a greater distance, or by deadening its effects by the
interposition of a medium, which may weaken and not destroy the object;
or by the admission of its reflection where the direct impression is
too strong, as that of the sun in a basin of water.

The seventh case, where the senses are so overcharged with the object
as to leave no further room, scarcely occurs except in the smell or
taste, and is not of much consequence as regards our present subject.
Let what we have said, therefore, suffice with regard to the reduction
to the sensible sphere of objects not naturally within its compass.

Sometimes, however, this reduction is not extended to the senses of
man, but to those of some other animal, whose senses, in some points,
exceed those of man; as (with regard to some scents) to that of the
dog, and with regard to light existing imperceptibly in the air, when
not illuminated from any extraneous source, to the sense of the cat,
the owl, and other animals which see by night. For Telesius has well
observed, that there appears to be an original portion of light even
in the air itself,[140] although but slight and meagre, and of no use
for the most part to the eyes of men, and those of the generality
of animals; because those animals to whose senses this light is
proportioned can see by night, which does not, in all probability,
proceed from their seeing either without light or by any internal light.

Here, too, we would observe, that we at present discuss only the
wants of the senses, and their remedies; for their deceptions must be
referred to the inquiries appropriated to the senses, and sensible
objects; except that important deception, which makes them define
objects in their relation to man, and not in their relation to the
universe, and which is only corrected by universal reasoning and
philosophy. [141]

XLI. In the eighteenth rank of prerogative instances we will class the
instances of the road, which we are also wont to call itinerant and
jointed instances. They are such as indicate the gradually continued
motions of nature. This species of instances escapes rather our
observation than our senses; for men are wonderfully indolent upon
this subject, consulting nature in a desultory manner, and at periodic
intervals, when bodies have been regularly finished and completed,
and not during her work. But if any one were desirous of examining
and contemplating the talents and industry of an artificer, he would
not merely wish to see the rude materials of his art, and then his
work when finished, but rather to be present while he is at labor,
and proceeding with his work. Something of the same kind should be
done with regard to nature. For instance, if any one investigate the
vegetation of plants, he should observe from the first sowing of any
seed (which can easily be done, by pulling up every day seeds which
have been two, three, or four days in the ground, and examining them
diligently), how and when the seed begins to swell and break, and be
filled, as it were, with spirit; then how it begins to burst the bark
and push out fibres, raising itself a little at the same time, unless
the ground be very stiff; then how it pushes out these fibres, some
downward for roots, others upward for the stem, sometimes also creeping
laterally, if it find the earth open and more yielding on one side, and
the like. The same should be done in observing the hatching of eggs,
where we may easily see the process of animation and organization, and
what parts are formed of the yolk, and what of the white of the egg,
and the like. The same may be said of the inquiry into the formation
of animals from putrefaction; for it would not be so humane to inquire
into perfect and terrestrial animals, by cutting the fœtus from the
womb; but opportunities may perhaps be offered of abortions, animals
killed in hunting, and the like. Nature, therefore, must, as it were,
be watched, as being more easily observed by night than by day: for
contemplations of this kind may be considered as carried on by night,
from the minuteness and perpetual burning of our watch-light.

The same must be attempted with inanimate objects, which we have
ourselves done by inquiring into the opening of liquids by fire.
For the mode in which water expands is different from that observed
in wine, vinegar, or verjuice, and very different, again, from that
observed in milk and oil, and the like; and this was easily seen by
boiling them with slow heat, in a glass vessel, through which the
whole may be clearly perceived. But we merely mention this, intending
to treat of it more at large and more closely when we come to the
discovery of the latent process; for it should always be remembered
that we do not here treat of things themselves, but merely propose
examples. [142]

XLII. In the nineteenth rank of prerogative instances we will class
supplementary or substitutive instances, which we are also wont to call
instances of refuge. They are such as supply information, where the
senses are entirely deficient, and we therefore have recourse to them
when appropriate instances cannot be obtained. This substitution is
twofold, either by approximation or by analogy. For instance, there is
no known medium which entirely prevents the effect of the magnet in
attracting iron--neither gold, nor silver, nor stone, nor glass, wood,
water, oil, cloth, or fibrous bodies, air, flame, or the like. Yet by
accurate experiment, a medium may perhaps be found which would deaden
its effect, more than another comparatively and in degree; as, for
instance, the magnet would not perhaps attract iron through the same
thickness of gold as of air, or the same quantity of ignited as of cold
silver, and so on; for we have not ourselves made the experiment, but
it will suffice as an example. Again, there is no known body which is
not susceptible of heat, when brought near the fire; yet air becomes
warm much sooner than stone. These are examples of substitution by
approximation.

Substitution by analogy is useful, but less sure, and therefore to be
adopted with some judgment. It serves to reduce that which is not the
object of the senses to their sphere, not by the perceptible operations
of the imperceptible body, but by the consideration of some similar
perceptible body. For instance, let the subject for inquiry be the
mixture of spirits, which are invisible bodies. There appears to be
some relation between bodies and their sources or support. Now, the
source of flame seems to be oil and fat; that of air, water, and watery
substances; for flame increases over the exhalation of oil, and air
over that of water. One must therefore consider the mixture of oil and
water, which is manifest to the senses, since that of air and flame in
general escapes the senses. But oil and water mix very imperfectly by
composition or stirring, while they are exactly and nicely mixed in
herbs, blood, and the parts of animals. Something similar, therefore,
may take place in the mixture of flame and air in spirituous
substances, not bearing mixture very well by simple collision, while
they appear, however, to be well mixed in the spirits of plants and
animals.

Again, if the inquiry do not relate to perfect mixtures of spirits,
but merely to their composition, as whether they easily incorporate
with each other, or there be rather (as an example) certain winds and
exhalations, or other spiritual bodies, which do not mix with common
air, but only adhere to and float in it in globules and drops, and
are rather broken and pounded by the air, than received into, and
incorporated with it; this cannot be perceived in common air, and other
aëriform substances, on account of the rarity of the bodies, but an
image, as it were, of this process may be conceived in such liquids
as quicksilver, oil, water, and even air, when broken and dissipated
it ascends in small portions through water, and also in the thicker
kinds of smoke; lastly, in dust, raised and remaining in the air, in
all of which there is no incorporation: and the above representation
in this respect is not a bad one, if it be first diligently
investigated, whether there can be such a difference of nature between
spirituous substances, as between liquids, for then these images might
conveniently be substituted by analogy.

And although we have observed of these supplementary instances, that
information is to be derived from them, when appropriate instances are
wanting, by way of refuge, yet we would have it understood, that they
are also of great use, when the appropriate instances are at hand, in
order to confirm the information afforded by them; of which we will
speak more at length, when our subject leads us, in due course, to the
support of induction.

XLIII. In the twentieth rank of prerogative instances we will place
lancing instances, which we are also wont (but for a different reason)
to call twitching instances. We adopt the latter name, because they
twitch the understanding, and the former because they pierce nature,
whence we style them occasionally the instances of Democritus. [143]
They are such as warn the understanding of the admirable and
exquisite subtilty of nature, so that it becomes roused and awakened
to attention, observation, and proper inquiry; as, for instance,
that a little drop of ink should be drawn out into so many letters;
that silver merely gilt on its surface should be stretched to such a
length of gilt wire; that a little worm, such as you may find on the
skin, should possess both a spirit and a varied conformation of its
parts; that a little saffron should imbue a whole tub of water with
its color; that a little musk or aroma should imbue a much greater
extent of air with its perfume; that a cloud of smoke should be
raised by a little incense; that such accurate differences of sounds
as articulate words should be conveyed in all directions through the
air, and even penetrate the pores of wood and water (though they
become much weakened), that they should be, moreover, reflected, and
that with such distinctness and velocity; that light and color should
for such an extent and so rapidly pass through solid bodies, such as
glass and water, with so great and so exquisite a variety of images,
and should be refracted and reflected; that the magnet should attract
through every description of body, even the most compact; but (what
is still more wonderful) that in all these cases the action of one
should not impede that of another in a common medium, such as air;
and that there should be borne through the air, at the same time, so
many images of visible objects, so many impulses of articulation, so
many different perfumes, as of the violet, rose, etc. , besides cold and
heat, and magnetic attractions; all of them, I say, at once, without
any impediment from each other, as if each had its paths and peculiar
passage set apart for it, without infringing against or meeting each
other.

To these lancing instances, however, we are wont, not without some
advantage, to add those which we call the limits of such instances.
Thus, in the cases we have pointed out, one action does not disturb or
impede another of a different nature, yet those of a similar nature
subdue and extinguish each other; as the light of the sun does that of
the candle, the sound of a cannon that of the voice, a strong perfume a
more delicate one, a powerful heat a more gentle one, a plate of iron
between the magnet and other iron the effect of the magnet. But the
proper place for mentioning these will be also among the supports of
induction.

XLIV. We have now spoken of the instances which assist the senses,
and which are principally of service as regards information; for
information begins from the senses. But our whole labor terminates in
practice, and as the former is the beginning, so is the latter the
end of our subject. The following instances, therefore, will be those
which are chiefly useful in practice. They are comprehended in two
classes, and are seven in number. We call them all by the general name
of practical instances. Now there are two defects in practice, and as
many divisions of important instances. Practice is either deceptive or
too laborious. It is generally deceptive (especially after a diligent
examination of natures), on account of the power and actions of
bodies being ill defined and determined. Now the powers and actions
of bodies are defined and determined either by space or by time, or
by the quantity at a given period, or by the predominance of energy;
and if these four circumstances be not well and diligently considered,
the sciences may indeed be beautiful in theory, but are of no effect
in practice. We call the four instances referred to this class,
mathematical instances and instances of measure.

Practice is laborious either from the multitude of instruments, or
the bulk of matter and substances requisite for any given work. Those
instances, therefore, are valuable, which either direct practice to
that which is of most consequence to mankind, or lessen the number of
instruments or of matter to be worked upon. We assign to the three
instances relating to this class, the common name of propitious or
benevolent instances. We will now separately discuss these seven
instances, and conclude with them that part of our work which relates
to the prerogative or illustrious instances.

XLV. In the twenty-first rank of prerogative instances we will place
the instances of the rod or rule, which we are also wont to call the
instances of completion or _non ultrà_. For the powers and motions of
bodies do not act and take effect through indefinite and accidental,
but through limited and certain spaces; and it is of great importance
to practice that these should be understood and noted in every nature
which is investigated, not only to prevent deception, but to render
practice more extensive and efficient. For it is sometimes possible to
extend these powers, and bring the distance, as it were, nearer, as in
the example of telescopes.

Many powers act and take effect only by actual touch, as in the
percussion of bodies, where the one does not remove the other, unless
the impelling touch the impelled body. External applications in
medicine, as ointment and plasters, do not exercise their efficacy
except when in contact with the body. Lastly, the objects of touch and
taste only strike those senses when in contact with their organs.

Other powers act at a distance, though it be very small, of which but
few have as yet been noted, although there be more than men suspect;
this happens (to take everyday instances) when amber or jet attracts
straws, bubbles dissolve bubbles, some purgative medicines draw humors
from above, and the like. The magnetic power by which iron and the
magnet, or two magnets, are attracted together, acts within a definite
and narrow sphere, but if there be any magnetic power emanating from
the earth a little below its surface, and affecting the needle in its
polarity, it must act at a great distance.

Again, if there be any magnetic force which acts by sympathy between
the globe of the earth and heavy bodies, or between that of the moon
and the waters of the sea (as seems most probable from the particular
floods and ebbs which occur twice in the month), or between the starry
sphere and the planets, by which they are summoned and raised to their
apogees, these must all operate at very great distances. [144]

Again, some conflagrations and the kindling of flames take place
at very considerable distances with particular substances, as they
report of the naphtha of Babylon. Heat, too, insinuates itself at wide
distances, as does also cold, so that the masses of ice which are
broken off and float upon the Northern Ocean, and are borne through the
Atlantic to the coast of Canada, become perceptible by the inhabitants,
and strike them with cold from a distance. Perfumes also (though here
there appears to be always some corporeal emission) act at remarkable
distances, as is experienced by persons sailing by the coast of
Florida, or parts of Spain, where there are whole woods of lemons,
oranges, and other odoriferous plants, or rosemary and marjoram bushes,
and the like. Lastly, the rays of light and the impressions of sound
act at extensive distances.

Yet all these powers, whether acting at a small or great distance,
certainly act within definite distances, which are well ascertained
by nature, so that there is a limit depending either on the mass or
quantity of the bodies, the vigor or faintness of the powers, or the
favorable or impeding nature of the medium, all of which should be
taken into account and observed. We must also note the boundaries of
violent motions, such as missiles, projectiles, wheels and the like,
since they are also manifestly confined to certain limits.

Some motions and virtues are to be found of a directly contrary nature
to these, which act in contact but not at a distance; namely, such as
operate at a distance and not in contact, and again act with less force
at a less distance, and the reverse. Sight, for instance, is not easily
effective in contact, but requires a medium and distance; although I
remember having heard from a person deserving of credit, that in being
cured of a cataract (which was done by putting a small silver needle
within the first coat of the eye, to remove the thin pellicle of the
cataract, and force it into a corner of the eye), he had distinctly
seen the needle moving across the pupil. Still, though this may be
true, it is clear that large bodies cannot be seen well or distinctly,
unless at the vertex of a cone, where the rays from the object meet
at some distance from the eye. In old persons the eye sees better if
the object be moved a little further, and not nearer. Again, it is
certain that in projectiles the impact is not so violent at too short
a distance as a little afterward. [145] Such are the observations to be
made on the measure of motions as regards distance.

There is another measure of motion in space which must not be passed
over, not relating to progressive but spherical motion--that is,
the expansion of bodies into a greater, or their contraction into a
lesser sphere. For in our measure of this motion we must inquire what
degree of compression or extension bodies easily and readily admit of,
according to their nature, and at what point they begin to resist it,
so as at last to bear it no further--as when an inflated bladder is
compressed, it allows a certain compression of the air, but if this be
increased, the air does not suffer it, and the bladder is burst.

We have proved this by a more delicate experiment. We took a metal
bell, of a light and thin sort, such as is used for salt-cellars, and
immersed it in a basin of water, so as to carry the air contained in
its interior down with it to the bottom of the basin. We had first,
however, placed a small globe at the bottom of the basin, over which
we placed the bell. The result was, that if the globe were small
compared with the interior of the bell, the air would contract itself,
and be compressed without being forced out, but if it were too large
for the air readily to yield to it, the latter became impatient of the
pressure, raised the bell partly up, and ascended in bubbles.

To prove, also, the extension (as well as the compression) which air
admits of, we adopted the following method:--We took a glass egg, with
a small hole at one end; we drew out the air by violent suction at
this hole, and then closed the hole with the finger, immersed the egg
in water, and then removed the finger. The air being constrained by
the effort made in suction, and dilated beyond its natural state, and
therefore striving to recover and contract itself (so that if the egg
had not been immersed in water, it would have drawn in the air with a
hissing sound), now drew in a sufficient quantity of water to allow
the air to recover its former dimensions. [146]

It is well ascertained that rare bodies (such as air) admit of
considerable contraction, as has been before observed; but tangible
bodies (such as water) admit of it much less readily, and to a less
extent. We investigated the latter point by the following experiment:

We had a leaden globe made, capable of containing about two pints, wine
measure, and of tolerable thickness, so as to support considerable
pressure. We poured water into it through an aperture, which we
afterward closed with melted lead, as soon as the globe was filled with
water, so that the whole became perfectly solid. We next flattened the
two opposite sides with a heavy hammer, which necessarily caused the
water to occupy a less space, since the sphere is the solid of greatest
content; and when hammering failed from the resistance of the water,
we made use of a mill or press, till at last the water, refusing to
submit to a greater pressure, exuded like a fine dew through the solid
lead. We then computed the extent to which the original space had been
reduced, and concluded that water admitted such a degree of compression
when constrained by great violence.

The more solid, dry or compact bodies, such as stones, wood and metals,
admit of much less, and indeed scarcely any perceptible compression or
expansion, but escape by breaking, slipping forward, or other efforts;
as appears in bending wood, or steel for watch-springs, in projectiles,
hammering and many other motions, all of which, together with their
degrees, are to be observed and examined in the investigation of
nature, either to a certainty, or by estimation, or comparison, as
opportunity permits.

XLVI. In the twenty-second rank of prerogative instances we will
place the instances of the course, which we are also wont to call
water instances, borrowing our expression from the water hour-glasses
employed by the ancients instead of those with sand. They are such as
measure nature by the moments of time, as the last instances do by the
degrees of space. For all motion or natural action takes place in time,
more or less rapidly, but still in determined moments well ascertained
by nature. Even those actions which appear to take effect suddenly, and
in the twinkling of an eye (as we express it), are found to admit of
greater or less rapidity.

In the first place, then, we see that the return of the heavenly bodies
to the same place takes place in regular times, as does the flood and
ebb of the sea. The descent of heavy bodies toward the earth, and
the ascent of light bodies toward the heavenly sphere, take place in
definite times,[147] according to the nature of the body, and of the
medium through which it moves. The sailing of ships, the motions of
animals, the transmission of projectiles, all take place in times
the sums of which can be computed. With regard to heat, we see that
boys in winter bathe their hands in the flame without being burned;
and conjurers, by quick and regular movements, overturn vessels filled
with wine or water, and replace them without spilling the liquid, with
several similar instances. The compression, expansion and eruption
of several bodies, take place more or less rapidly, according to the
nature of the body and its motion, but still in definite moments.

In the explosion of several cannon at once (which are sometimes heard
at the distance of thirty miles), the sound of those nearest to the
spot is heard before that of the most distant. Even in sight (whose
action is most rapid), it is clear that a definite time is necessary
for its exertion, which is proved by certain objects being invisible
from the velocity of their motion, such as a musket-ball; for the
flight of the ball is too swift to allow an impression of its figure to
be conveyed to the sight.

This last instance, and others of a like nature, have sometimes excited
in us a most marvellous doubt, no less than whether the image of the
sky and stars is perceived as at the actual moment of its existence,
or rather a little after, and whether there is not (with regard to the
visible appearance of the heavenly bodies) a true and apparent time,
as well as a true and apparent place, which is observed by astronomers
in parallaxes. It appeared so incredible to us, that the images or
radiations of heavenly bodies could suddenly be conveyed through such
immense spaces to the sight, and it seemed that they ought rather to be
transmitted in a definite time. [148] That doubt, however (as far as
regards any great difference between the true and apparent time), was
subsequently completely set at rest, when we considered the infinite
loss and diminution of size as regards the real and apparent magnitude
of a star, occasioned by its distance, and at the same time observed
at how great a distance (at least sixty miles) bodies which are merely
white can be suddenly seen by us. For there is no doubt, that the light
of the heavenly bodies not only far surpasses the vivid appearance of
white, but even the light of any flame (with which we are acquainted)
in the vigor of its radiation. The immense velocity of the bodies
themselves, which is perceived in their diurnal motion, and has so
astonished thinking men, that they have been more ready to believe in
the motion of the earth, renders the motion of radiation from them
(marvellous as it is in its rapidity) more worthy of belief. That
which has weighed most with us, however, is, that if there were any
considerable interval of time between the reality and the appearance,
the images would often be interrupted and confused by clouds formed in
the meantime, and similar disturbances of the medium. Let this suffice
with regard to the simple measures of time.

It is not merely the absolute, but still more the relative measure of
motions and actions which must be inquired into, for this latter is
of great use and application. We perceive that the flame of firearms
is seen sooner than the sound is heard, although the ball must have
struck the air before the flame, which was behind it, could escape:
the reason of which is, that light moves with greater velocity than
sound. We perceive, also, that visible images are received by the sight
with greater rapidity than they are dismissed, and for this reason, a
violin string touched with the finger appears double or triple, because
the new image is received before the former one is dismissed. Hence,
also, rings when spinning appear globular, and a lighted torch, borne
rapidly along at night, appears to have a tail. Upon the principle of
the inequality of motion, also, Galileo attempted an explanation of
the flood and ebb of the sea, supposing the earth to move rapidly, and
the water slowly, by which means the water, after accumulating, would
at intervals fall back, as is shown in a vessel of water made to move
rapidly. He has, however, imagined this on data which cannot be granted
(namely, the earth’s motion), and besides, does not satisfactorily
account for the tide taking place every six hours.

An example of our present point (the relative measure of motion), and,
at the same time, of its remarkable use of which we have spoken, is
conspicuous in mines filled with gunpowder, where immense weights of
earth, buildings, and the like, are overthrown and prostrated by a
small quantity of powder; the reason of which is decidedly this, that
the motion of the expansion of the gunpowder is much more rapid than
that of gravity,[149] which would resist it, so that the former has
terminated before the latter has commenced. Hence, also, in missiles,
a strong blow will not carry them so far as a sharp and rapid one.
Nor could a small portion of animal spirit in animals, especially in
such vast bodies as those of the whale and elephant, have ever bent or
directed such a mass of body, were it not owing to the velocity of the
former, and the slowness of the latter in resisting its motion.

In short, this point is one of the principal foundations of the magic
experiments (of which we shall presently speak), where a small mass
of matter overcomes and regulates a much larger, if there but be an
anticipation of motion, by the velocity of one before the other is
prepared to act.

Finally, the point of the first and last should be observed in all
natural actions. Thus, in an infusion of rhubarb the purgative property
is first extracted, and then the astringent; we have experienced
something of the same kind in steeping violets in vinegar, which first
extracts the sweet and delicate odor of the flower, and then the
more earthy part, which disturbs the perfume; so that if the violets
be steeped a whole day, a much fainter perfume is extracted than if
they were steeped for a quarter of an hour only, and then taken out;
and since the odoriferous spirit in the violet is not abundant, let
other and fresh violets be steeped in the vinegar every quarter of an
hour, as many as six times, when the infusion becomes so strengthened,
that although the violets have not altogether remained there for more
than one hour and a half, there remains a most pleasing perfume, not
inferior to the flower itself, for a whole year. It must be observed,
however, that the perfume does not acquire its full strength till
about a month after the infusion. In the distillation of aromatic
plants macerated in spirits of wine, it is well known that an aqueous
and useless phlegm rises first, then water containing more of the
spirit, and, lastly, water containing more of the aroma; and many
observations of the like kind, well worthy of notice, are to be made in
distillations. But let these suffice as examples. [150]

XLVII. In the twenty-third rank of prerogative instances we will place
instances of quantity, which we are also wont to call the doses of
nature (borrowing a word from medicine). They are such as measure the
powers by the quantity of bodies, and point out the effect of the
quantity in the degree of power. And in the first place, some powers
only subsist in the universal quantity, or such as bears a relation to
the confirmation and fabric of the universe. Thus the earth is fixed,
its parts fall. The waters in the sea flow and ebb, but not in the
rivers, except by the admission of the sea. Then, again, almost all
particular powers act according to the greater or less quantity of the
body. Large masses of water are not easily rendered foul, small are.
New wine and beer become ripe and drinkable in small skins much more
readily than in large casks. If a herb be placed in a considerable
quantity of liquid, infusion takes place rather than impregnation;
if in less, the reverse. A bath, therefore, and a light sprinkling,
produce different effects on the human body. Light dew, again, never
falls, but is dissipated and incorporated with the air; thus we see
that in breathing on gems, the slight quantity of moisture, like a
small cloud in the air, is immediately dissolved. Again, a piece of
the same magnet does not attract so much iron as the whole magnet did.
There are some powers where the smallness of the quantity is of more
avail; as in boring, a sharp point pierces more readily than a blunt
one; the diamond, when pointed, makes an impression on glass, and the
like.

Here, too, we must not rest contented with a vague result, but inquire
into the exact proportion of quantity requisite for a particular
exertion of power; for one would be apt to suppose that the power bears
an exact proportion to the quantity; that if a leaden bullet of one
ounce, for instance, would fall in a given time, one of two ounces
ought to fall twice as rapidly, which is most erroneous. Nor does the
same ratio prevail in every kind of power, their difference being
considerable. The measure, therefore, must be determined by experiment,
and not by probability or conjecture.

Lastly, we must in all our investigations of nature observe what
quantity, or dose, of the body is requisite for a given effect, and
must at the same time be guarded against estimating it at too much or
too little.

XLVIII. In the twenty-fourth rank of prerogative instances we will
place wrestling instances, which we are also wont to call instances
of predominance. They are such as point out the predominance and
submission of powers compared with each other, and which of them is the
more energetic and superior, or more weak and inferior. For the motions
and effects of bodies are compounded, decomposed, and combined, no less
than the bodies themselves. We will exhibit, therefore, the principal
kinds of motions or active powers, in order that their comparative
strength, and thence a demonstration and definition of the instances in
question, may be rendered more clear.

Let the first motion be that of the resistance of matter, which exists
in every particle, and completely prevents its annihilation; so that
no conflagration, weight, pressure, violence, or length of time can
reduce even the smallest portion of matter to nothing, or prevent it
from being something, and occupying some space, and delivering itself
(whatever straits it be put to), by changing its form or place, or, if
that be impossible, remaining as it is; nor can it ever happen that it
should either be nothing or nowhere. This motion is designated by the
schools (which generally name and define everything by its effects and
inconveniences rather than by its inherent cause) by the axiom, that
two bodies cannot exist in the same place, or they call it a motion to
prevent the penetration of dimensions. It is useless to give examples
of this motion, since it exists in every body.

Let the second motion be that which we term the motion of connection,
by which bodies do not allow themselves to be separated at any point
from the contact of another body, delighting, as it were, in the
mutual connection and contact. This is called by the schools a motion
to prevent a vacuum. It takes place when water is drawn up by suction
or a syringe, the flesh by cupping, or when the water remains without
escaping from perforated jars, unless the mouth be opened to admit the
air, and innumerable instances of a like nature.

Let the third be that which we term the motion of liberty, by which
bodies strive to deliver themselves from any unnatural pressure or
tension, and to restore themselves to the dimensions suited to their
mass; and of which, also, there are innumerable examples. Thus, we have
examples of their escaping from pressure, in the water in swimming, in
the air in flying, in the water again in rowing, and in the air in the
undulation of the winds, and in springs of watches. An exact instance
of the motion of compressed air is seen in children’s popguns, which
they make by scooping out elder-branches or some such matter, and
forcing in a piece of some pulpy root or the like, at each end; then
they force the root or other pellet with a ramrod to the opposite end,
from which the lower pellet is emitted and projected with a report,
and that before it is touched by the other piece of root or pellet,
or by the ramrod. We have examples of their escape from tension, in
the motion of the air that remains in glass eggs after suction, in
strings, leather, and cloth, which recoil after tension, unless it be
long continued. The schools define this by the term of motion from the
form of the element; injudiciously enough, since this motion is to be
found not only in air, water, or fire, but in every species of solid,
as wood, iron, lead, cloth, parchment, etc. , each of which has its own
proper size, and is with difficulty stretched to any other. Since,
however, this motion of liberty is the most obvious of all, and to be
seen in an infinite number of cases, it will be as well to distinguish
it correctly and clearly; for some most carelessly confound this with
the two others of resistance and connection; namely, the freedom from
pressure with the former, and that from tension with the latter, as if
bodies when compressed yielded or expanded to prevent a penetration of
dimensions, and when stretched rebounded and contracted themselves to
prevent a vacuum.