No More Learning

This
comes out with particular clearness in the metaphysical interpretation
put on the logical process of definition by genus and difference. When
I define any real kind by specifying a higher and wider class of which
it is a sub-kind, and adding the peculiar characteristics which
distinguish the sub-kind under consideration from the other sub-kinds of
the same genus, the genus may be said to stand to the "differences" as
Matter, the relatively indeterminate, to the Form which gives it its
structure.

We further observe that Matter and Form are strictly correlative. The
matter is called so relatively to the form which gives it further
determination. When the words are used in their strictest sense, with
reference to an individual thing, the Form is taken to mean the _last_
determination by which the thing acquires its complete character, and
the Matter is that which has yet to receive this last determination.
Thus in the case of a copper globe, the spherical figure is said to be
its Form, the copper its material. In the case of the human body, the
Matter is the various tissues, muscles, bones, skin, &c. But each of
these things which are counted as belonging to the Matter of the globe
or the human body has, according to Aristotle, a development behind it.
Copper is not an "element" but a specific combination of "elements," and
the same thing is even more true of the highly elaborate tissues of the
living body. Thus what is Matter relatively to the globe or living body
is Matter already determined by Form if we consider it relatively to its
own constituents. The so-called "elements" of Empedocles, earth, water,
air, fire, are the matter of all chemical compounds, the Form of each
compound being its specific law of composition; the immediate or
"proximate" Matter of the tissues of the animal body is, according to
Aristotle's biology, the "superfluous" blood of the female parent, out
of which the various tissues in the offspring are developed, and the
Matter of this blood is in turn the various substances which are taken
into the body of the parent as food and converted by assimilation into
blood. Their Matter, once more, is the earth, air, fire, and water of
which they are composed. Thus at every stage of a process of manufacture
or growth a fresh Form is superinduced on, or developed within, a Matter
which is already itself a combination of Matter and Form relatively to
the process by which it has itself been originated. Fully thought out,
such a view would lead to the conclusion that in the end the simple
ultimate matter of all individual things is one and the same throughout
the universe, and has absolutely no definite structure at all. The
introduction of Form or determinate structure of any kind would then
have to be thought of as coming from an outside source, since
structureless Matter cannot be supposed to give itself all sorts of
specific determinations, as has been demonstrated in our own times by
the collapse of the "Synthetic Philosophy. " Aristotle avoids the
difficulty by holding that "pure Matter" is a creation of our thought.
In actual fact the crudest form in which matter is found is that of the
"elements. " Since the transmutability of the "elements" is an
indispensable tenet in Aristotle's Physics, we cannot avoid regarding
earth, water, fire air as themselves determinations by specific Form of
a still simpler Matter, though this "prime Matter" "all alone, before a
rag of Form is on," is never to be found existing in its simplicity. [#]


[#] _Hudibras_, Pt. 1, Canto 1, 560.

"He had First Matter seen undressed;
He took her naked all alone,
Before one rag of Form was on. "


*The Potential and the Actual*. --So far we have been looking at the
analysis of the individual thing, as the current jargon puts it,
statically; we have arrived at the antithesis of Matter and Form by
contrasting an unfinished condition of anything with its finished
condition. But we may study the same contrast dynamically, with special
reference to the process of making or growth by which the relatively
undetermined or unfinished becomes determined or finished. The contrast
of Matter with Form then passes into the contrast between Potentiality
and Actuality. What this antithesis means we can best see from the case
of the growth of a living organism. Consider the embryos of two animals,
or the seeds of two plants. Even a botanist or a physiologist may be
unable to pronounce with certainty on the species to which the germ
submitted to him belongs, and chemical analysis may be equally at a
loss. Even at a later stage of development, the embryo of one
vertebrate animal may be indistinguishable from that of another. Yet it
is certain that one of two originally indistinguishable germs will grow
into an oak and the other into an elm, or one into a chimpanzee and the
other into a man. However indistinguishable, they therefore may be said
to have different latent tendencies or possibilities of development
within them. Hence we may say of a given germ, "though this is not yet
actually an oak, it is potentially an oak," meaning not merely that, if
uninterfered with, it will in time be an oak, but also that by no
interference can it be made to grow into an elm or a beech. So we may
look upon all processes of production or development as processes by
which what at first possessed only the tendency to grow along certain
lines or to be worked up into a certain form, has become actually
endowed with the character to which it possessed the tendency. The
acorn becomes in process of time an actual oak, the baby an actual man,
the copper is made into an actual vase, right education brings out into
active exercise the special capacities of the learner. Hence the
distinction between Matter and Form may also be expressed by saying that
the Matter is the persistent underlying _substratum_ in which the
development of the Form takes place, or that the individual when finally
determined by the Form is the Actuality of which the undeveloped Matter
was the Potentiality. The process of conception, birth, and growth to
maturity in Nature, or of the production of a finished article by the
"arts" whose business it is to "imitate" Nature, may be said to be one
of continuous advance towards the actual embodiment of a Form, or law of
organisation, in a Matter having the latent potentiality of developing
along those special lines. When Aristotle is speaking most strictly he
distinguishes the process by which a Form is realised, which he calls
Energeia, from the manifestation of the realised Form, calling the
latter Entelechy (literally "finished" or "completed" condition).
Often, however, he uses the word Energeia more loosely for the actual
manifestation of the Form itself, and in this he is followed by the
scholastic writers, who render Energeia by _actus_ or _actus purus_.

One presupposition of this process must be specially noted. It is not an
unending process of development of unrealised capacities, but always has
an End in the perfectly simple sense of a last stage. We see this best
in the case of growth. The acorn grows into the sapling and the sapling
into the oak, but there is nothing related to the oak as the oak is to
the sapling. The oak does not grow into something else. The process of
development from potential to actual in this special case comes to an
end with the emergence of the mature oak. In the organic world the end
or last state is recognised by the fact that the organism can now
exercise the power of reproducing its like. This tendency of organic
process to culminate in a last stage of complete maturity is the key to
the treatment of the problem of the "true end" of life in Aristotle's
_Ethics_.

*The Four Causes*. --The conception of the world involved in these
antitheses of Form and Matter, Potential and Actual, finds its fullest
expression in Aristotle's doctrine of the Four Causes or conditions of
the production of things. This doctrine is looked on by Aristotle as
the final solution of the problem which had always been the central one
for Greek philosophy, What are the causes of the world-order? All the
previous philosophies he regards as inadequate attempts to formulate the
answer to this question which is only given completely by his own
system. Hence the doctrine requires to be stated with some fullness.
We may best approach it by starting from the literal meaning of the
Greek terms _aitia_, _aition_, which Aristotle uses to convey the notion
of cause. _Aition_ is properly an adjective used substantially, and
means "that on which the legal responsibility for a given state of
affairs can be laid. " Similarly _aitia_, the substantive, means the
"credit" for good or bad, the legal "responsibility," for an act. Now
when we ask, "what is responsible for the fact that such and such a
state of things now exists? " there are four partial answers which may be
given, and each of these corresponds to one of the "causes. " A complete
answer requires the enumeration of them all. We may mention (1) the
_matter_ or _material_ cause of the thing, (2) the law according to
which it has grown or developed, the _form_ or _formal_ cause, (3) the
agent with whose initial impulse the development began--the
"starting-point of the process," or, as the later Aristotelians call it,
the _efficient_ cause, (4) the completed result of the whole process,
which is present in the case of human manufacture as a preconceived idea
determining the maker's whole method of handling his material, and in
organic development in Nature as implied in and determining the
successive stages of growth--the _end_ or _final_ cause. If any one of
these had been different, the resultant state of things would also have
been different. Hence all four must be specified in completely
accounting for it. Obvious illustrations can be given from artificial
products of human skill, but it seems clear that it was rather
reflection on the biological process of reproduction and growth which
originally suggested the analysis. Suppose we ask what was requisite in
order that there should be now an oak on a given spot. There must have
been (1) a germ from which the oak has grown, and this germ must have
had the latent tendencies towards development which are characteristic
of oaks. This is the material cause of the oak. (2) This germ must
have followed a definite law of growth; it must have had a tendency to
grow in the way characteristic of oaks and to develop the structure of
an oak, not that of a plane or an ash. This is form or formal cause.
(3) Also the germ of the oak did not come from nowhere; it grew on a
parent oak. The parent oak and its acorn-bearing activity thus
constitute the _efficient_ cause of the present oak. (4) And there must
be a final stage to which the whole process of growth is relative, in
which the germ or sapling is no longer becoming but is an adult oak
bearing fresh acorns. This is the _end_ of the process. One would not
be going far wrong in saying that Aristotle's biological cast of thought
leads him to conceive of this "end" in the case of reproduction as a
sub-conscious purpose, just as the workman's thought of the result to be
attained by his action forms a conscious directing purpose in the case
of manufacture. Both in Nature and in "art" the "form," the "efficient
cause," and the "end" tend to coalesce. Thus in Nature "a man begets a
man," organic beings give birth to other organic beings of the same
kind, or, in the technical language of the Aristotelian theory of
Causation, the efficient cause produces, as the "end" of its action, a
second being having the same "form" as itself, though realised in
different "matter," and numerically distinct from itself. Thus the
efficient cause (_i. e. _ the parent) is a "form" realised in matter, and
the "end" is the same "form" realised in other matter. So in "products
of art" the true "source of the process" is the "form" the realisation
of which is the "end" or final cause, only with this difference, that as
efficient cause the "form" exists not in the material but by way of
"idea" or "representation" in the mind of the craftsman. A house does
not produce another house, but the house as existing in "idea" in the
builder's mind sets him at work building, and so produces a
corresponding house in brick or stone. Thus the ultimate opposition is
between the "cause as matter," a passive and inert substratum of change
and development and the "formal" cause which, in the sense just
explained, is one with both the "efficient" or starting-point, and the
"end" or goal of development. It will, of course, be seen that
individual bearers of "forms" are indispensable in the theory; hence the
notion of _activity_ is essential to the causal relation. It is a
relation between things, not between events. Aristotle has no sense of
the word cause corresponding to Mill's conception of a cause as an event
which is the uniform precursor of another event.

Two more remarks may be made in this connection. (1) The prominence of
the notion of "end" gives Aristotle's philosophy a thorough-going
"ideological" character. God and Nature, he tells us, do nothing
aimlessly. We should probably be mistaken if we took this to mean that
"God and Nature" act everywhere with conscious design. The meaning is
rather that every natural process has a last stage in which the "form"
which was to begin with present in the agent or "source of change" is
fully realised in the matter in which the agent has set up the process
of change. The normal thing is _e. g. _ for animals to reproduce "their
kind"; if the reproduction is imperfect or distorted, as in monstrous
births, this is an exception due to the occasional presence in "matter"
of imperfections which hinder the course of development, and must be
regarded as "contrary to the normal course of Nature. " So hybrid
reproduction is exceptional and "against Nature," and this is shown by
the sterility of hybrids, a sort of lesser monstrosity. Even females,
being "arrested developments," are a sort of still minor deviation from
principle. (2) It may just be mentioned that Aristotle has a
classification of efficient causes under the three heads of Nature,
Intelligence (or Man), and Chance. The difference between Nature and
Man or Intelligence as efficient causes has already been illustrated.
It is that in causation by Nature, such as sexual reproduction, or the
assimilation of nutriment, or the conversion of one element into another
in which Aristotle believed, the form which is superinduced on the
matter by the agent already exists in the agent itself as _its_ form.
The oak springs from a parent oak, the conversion of nutriment into
organic tissue is due to the agency of already existing organic tissue.
In the case of human intelligence or art, the "form" to be superinduced
exists in the agent not as _his_ characteristic form, but by way of
representation, as a contemplated design. The man who builds a house is
not himself a house; the form characteristic of a house is very
different from that characteristic of a man, but it is present in
contemplation to the builder before it is embodied in the actual house.
A word may be added about the third sort of efficient causality,
causation by chance. This is confined to cases which are exceptions
from the general course of Nature, remarkable coincidences. It is what
we may call "simulated purposiveness. " When something in human affairs
happens in a way which subserves the achievement of a result but was not
really brought about by any intention to secure the result, we speak of
it as a remarkable coincidence. Thus it would be a coincidence if a man
should be held to ransom by brigands and his best friend should, without
knowing anything of the matter, turn up on the spot with the means of
ransoming him. The events could not have happened more opportunely if
they had been planned, and yet they were not planned but merely fell out
so: and since such a combination of circumstances simulating design is
unusual, it is not proper to say that the events happened "in the course
of Nature. " We therefore say it happened by chance. This doctrine of
chance has its significance for mediaeval Ethics. In an age when the
Protestant superstition that worldly success is proof of nearness to God
had not yet been invented, the want of correspondence between men's
"deserts" and their prosperity was accounted for by the view that the
distribution of worldly goods is, as a rule, the work of Fortune or
Chance in the Aristotelian sense; that is, it is due to special
coincidences which may look like deliberate design but are not really
so. (See the elaborate exposition of this in Dante, _Inferno_, vii.
67-97. )

*Motion*. --We have seen that causation, natural or artificial, requires
the production in a certain "matter" of a certain "form" under the
influence of a certain "agent. " What is the character of the process
set up by the agent in the matter and culminating in the appearance of
the form? Aristotle answers that it is Motion (_kinesis_). The effect
of the agent on the matter is to set up in it a motion which ends in its
assuming a definite form. The important point to be noted here is that
Aristotle regards this motion as falling wholly within the matter which
is to assume the form. It is not necessary that the agent should itself
be in motion, but only that it should induce motion in something else.
Thus in all cases of intentional action the ultimate efficient cause is
the "idea of the result to be attained," but this idea does not move
about. By its presence to the mind it sets something else (the members
of the body) moving. This conception of an efficient cause which, not
moving itself, by its mere presence induces movement in that to which it
is present, is of the highest importance in Aristotle's theology. Of
course it follows that since the motion by which the transition from
potentiality to actuality is achieved falls wholly within the matter
acted upon, Aristotle is not troubled with any of the questions as to
the way in which motion can be transferred from one body to another
which were so much agitated in the early days of the modern mechanical
interpretation of natural processes. Aristotle's way of conceiving
Nature is thoroughly non-mechanical, and approximates to what would now
be called the ascription of vital or quasi-vital characteristics to the
inorganic. As, in the causality of "art" the mere presence of the
"form" to be embodied in a given material to the mind of the craftsman
brings about and directs the process of manufacture, so in some
analogous fashion the presence of an efficient cause in Nature to that
on which it works is thought of as itself constituting the "efficiency"
of the cause. As Lotze phrases it, things "take note of" one another's
compresence in the universe, or we might say the efficient cause and
that on which it exercises its efficiency are _en rapport_. "Matter" is
sensitive to the presence of the "efficient cause," and in response to
this sensitivity, puts forth successive determinations, expands its
latent tendencies on definite lines.

The name "motion" has a wider sense for Aristotle than it has for
ourselves. He includes under the one common name all the processes by
which things come to be what they are or cease to be what they have
been. Thus he distinguishes the following varieties of "motion":
_generation_ (the coming of an individual thing into being), with its
opposite _decay_ or _corruption_ (the passing of a thing out of being),
_alteration_ (change of _quality_ in a thing), _augmentation_ and
_diminution_ (change in the _magnitude_ of a thing), _motion through
space_ (of which latter he recognises two sub-species, rectilinear
_transference_ and _rotation_ in a circular orbit about an axis). It is
this last variety, motion through space, which is the most fundamental
of all, since its occurrence is involved in that of any of the other
types of process mentioned, though Aristotle does not hold the
thorough-going mechanical view that the other processes are only
apparent, and that, as we should put it, qualitative change is a mere
disguise which mechanical motion wears for our senses.

*The Eternity of Motion*. --Certain very important consequences follow
from the conception of efficient causation which we have been
describing. Aristotle has no sympathy with the "evolutionist" views
which had been favoured by some of his predecessors. According to his
theory of organic generation, "it takes a man to beget a man "; where
there is a baby, there must have been a father. Biological kinds
representing real clefts in Nature, the process of the production of a
young generation by an already adult generation must be thought of as
without beginning and without end. There can be no natural "evolution"
of animals of one species from individuals of a different kind. Nor
does it occur to Aristotle to take into account the possibility of
"Creationism," the sudden coming into being of a fully fledged first
generation at a stroke. This possibility is excluded by the doctrine
that the "matter" of a thing must exist beforehand as an indispensable
condition of the production of that thing. Every baby, as we said, must
have had a father, but that father must also have been a baby before he
was a full-grown man. Hence the perpetuation of unchanging species must
be without beginning and without end. And it is implied that all the
various processes, within and without the organism, apart from which its
life could not be kept up, must be equally without beginning and without
end. The "cosmos," or orderly world of natural processes, is strictly
"eternal"; "motion" is everlasting and continuous, or unbroken. Even
the great Christian theologians who built upon Aristotle could not
absolutely break with him on this point. St. Thomas, though obliged to
admit that the world was actually created a few thousand years before
his own time, maintains that this can only be known to be true from
revelation, philosophically it is equably tenable that the world should
have been "created from all eternity. " And it is the general doctrine
of scholasticism that the expression "creation" only denotes the
absolute dependence of the world on God for its being. When we say "God
created the world out of nothing," we mean that He did not make it out
of pre-existing matter, that it depends for its being on Him only; the
expression is purely negative in its import.

*God*. --With the doctrine of the eternity of the world and the processes
which make up its life we come close to the culminating theory of
Aristotelian First Philosophy, its doctrine of God, as the eternal,
unchanging source of all change, movement, and process. All motion is a
process within matter by which the forms latent in it are brought into
actual manifestation. And the process only takes place in the presence
of an adequate efficient cause or source of motion. Hence the eternity
of natural processes involves the existence of one or more eternal
sources of motion. For, if we do not admit the existence of an
unoriginated and ever-present source or sources of motion, our only
alternative is to hold that the world-process is due to a series of
sources of motion existing successively. But such a view would leave the
unity and unbroken continuity of the world-process unaccounted for. It
would give us a succession of processes, temporally contiguous, not one
unbroken process. Hence we argue from the continuity of motion to its
dependence on a source or sources which are permanent and present
throughout the whole everlasting world-process. And when we come to the
question whether there is only one such ultimate source of movement for
the whole universe, or several, Aristotle's answer is that the supreme
"Unmoved Mover" is one. One is enough for the purpose, and the law of
parcimony forbids us to assume the superfluous. This then is the
Aristotelian conception of God and God's relation to the world. God is
the one supreme unchanging being to whose presence the world responds
with the whole process of cosmic development, the ultimate educer of the
series of "forms" latent in the "matter" of the world into actual
manifestation. Standing, as He does, outside the whole process which by
His mere presence He initiates in Nature, He is not himself a composite
of "form" and "matter," as the products of development are. He is a pure
individual "form" or "actuality," with no history of gradual development
behind it. Thus He is a purely immaterial being, indispensable to the
world's existence but transcending it and standing outside it. _How_
His presence inspires the world to move Aristotle tries to explain by
the metaphor of appetition. Just as the good I desire and conceive,
without itself "moving" "moves" my appetition, so God moves the universe
by being its good. This directly brings about a uniform unbroken
rotation of the whole universe round its axis (in fact, the alternation
of day and night). And since this rotation is communicated from the
outermost "sphere" of heaven to all the lesser "spheres" between it and
the immovable centre, the effects of God's presence are felt
universally. At the same time, we must note that though God is the
supreme Mover of the Universe, He is not regarded by Aristotle as its
Creator, even in the sense in which creation can be reconciled with the
eternity of the world. For the effect of God's presence is simply to
lead to the development of "form" in an already existing "matter. "
Without God there could be no "form" or order in things, not even as
much as is implied in the differentiation of matter into the four
"elements," yet "primary matter" is no less than God a precondition of
all that happens.

It is characteristic of Aristotle that his God is as far from
discharging the functions of a Providence as He is from being a Creator.
His "activity" is not, as Plato had made it, that of the great "Shepherd
of the sheep. " As far as the world is concerned, God's only function is
to be there to move its appetition. For the rest, the unbroken activity
of this life is directed wholly inward. Aristotle expressly calls it an
"activity of immobility. " More precisely, he tells us, it is activity
of thought, exercised unbrokenly and everlastingly upon the only object
adequate to exercise God's contemplation, Himself. His life is one of
everlasting _self_-contemplation or "thinking of thought itself. " Like
all unimpeded exercise of activity, it is attended by pleasure, and as
the activity is continuous, so the pleasure of it is continuous too. At
our best, when we give ourselves up to the pure contemplative activity
of scientific thought or aesthetic appreciation, we enter for a while
into this divine life and share the happiness of God. But that is a
theme for our chapter on the _Ethics_.

It is a far cry from this conception of a God untroubled by care for a
world to which He is only related as the object of its aspiration to the
God who cares even for the fall of the sparrow and of whom it is
written, _Sic Deus dilexit mundum_, but it was the standing task of the
philosophical theologians of the Middle Ages to fuse the two
conceptions. Plato's God, who, if not quite the Creator, is the "Father
and Fashioner" of us all, and keeps providential watch over the world He
has fashioned, would have lent Himself better to their purposes, but
Plato was held by the mediaeval church to have denied the resurrection of
the body. The combination of Aristotle's Theism with the Theism of
early Christianity was effected by exquisitely subtle logical devices,
but even in St. Thomas one cannot help seeing the seams.

Nor can one help seeing in Aristotle's own doctrine the usual want of
coherence between an initial anti-Platonic bias and a final reversion to
the very Platonic positions Aristotle is fond of impugning. We are told
at the outset that the Platonic "separate forms" are empty names, and
that the real individual thing is always a composite of matter and a
form which only exists "in matter. " We find in the end that the source
of the whole process by which "matter" becomes imbued with "form" is a
being which is "pure" form and stands outside the whole development
which its presence sets up. And the issue of Aristotle's warning against
"poetic metaphors" is the doctrine that God moves the world by being
"the object of the world's desire. "




*CHAPTER IV*

*PHYSICS*


There is no part of Aristotle's system which has been more carefully
thought out than his Physics; at the same time it is almost wholly on
account of his physical doctrines that his long ascendancy over thought
is so much to be regretted. Aristotle's qualifications as a man of
science have been much overrated. In one department, that of descriptive
natural history, he shows himself a master of minute and careful
observation who could obtain unqualified praise from so great a
naturalist as Darwin. But in Astronomy and Physics proper his
inferiority in mathematical thinking and his dislike for mechanical ways
of explaining facts put him at a great disadvantage, as compared with
Plato and Plato's Pythagorean friends. Thus his authority was for
centuries one of the chief influences which prevented the development of
Astronomy on right lines. Plato had himself both taught the mobility of
the earth and denied correctly that the earth is at the centre of the
universe, and the "Copernican" hypothesis in Astronomy probably
originated in the Academy. Aristotle, however, insists on the central
position of the earth, and violently attacks Plato for believing in its
motion. It is equally serious that he insists on treating the so-called
"four elements" as ultimately unanalysable forms of matter, though Plato
had not only observed that so far from being the ABC (_stoicheia_ or
_elementa_, literally, letters of the alphabet) of Nature they do not
deserve to be called even "syllables," but had also definitely put
forward the view that it is the geometrical structure of the
"corpuscles" of body upon which sensible qualities depend. It is on
this doctrine, of course, that all mathematical physics rests.
Aristotle reverts to the older theory that the differences between one
"element" and another are qualitative differences of a sensible kind.
Even in the biological sciences Aristotle shows an unfortunate proneness
to disregard established fact when it conflicts with the theories for
which he has a personal liking. Thus, though the importance of the
brain as the central organ of the sensori-motor system had been
discovered in the late sixth or early fifth century by the physician
Alemacon of Crotona, and taught by the great Hippocrates in the fifth
and by Plato in the fourth century, Aristotle's prejudices in favour of
the doctrines of a different school of biologists led him to revert to
the view that it is the heart which is the centre of what we now call
the "nervous system. " It is mainly on account of these reactionary
scientific views that he was attacked in the early seventeenth century
by writers like our own Francis Bacon, who found in veneration for
Aristotle one of the chief hindrances to the free development of natural
science. The same complaints had been made long before by critics
belonging to the Platonic Academy.
It is a Platonist of the time of
Marcus Aurelius who sums up a vigorous attack on the Aristotelian
astronomy by the remark that Aristotle never understood that the true
task of the physicist is not to prescribe laws to Nature, but to learn
from observation of the facts what the laws followed by Nature are.

In determining the scope of Physics, we have to begin by considering
what is the special characteristic of things produced by Nature as
contrasted with those produced by "art. " The obvious distinction,
intimated by the very etymology of the word "Nature" (_physis_,
connected with _phyesthai_, to grow, to be born, as _natura_ is with
_nasci_), is that "what is by Nature" is born and grows, whereas what is
as a result of artifice is _made_. The "natural" may thus be said to
consist of living bodies and of their constituent parts. Hence
inorganic matter also is included in "Nature," on the ground that living
tissue can be analysed back into compounds of the "elements. " Now
things which are alive and grow are distinguished from things which are
made by "a source of motion and quiescence within themselves"; all of
them exhibit motions, changes of quality, processes of growth and
decline which are initiated from within. Hence Nature may be defined as
the totality of things which have a source of motion internal to
themselves and of the constituent parts of such things. Nature then
comprises all beings capable of spontaneous change. Whatever either does
not change at all, or only changes in consequence of external
influences, is excluded from Nature.

Thus the fundamental fact everywhere present in Nature is "change,"
"process," "motion. " Since motion in the literal sense of change of
position is involved as a condition of every such process, and such
motion requires space through which to move and time to move in, the
doctrine of space and time will also form part of Physics. Hence a
great part of Aristotle's special lectures on Physics is occupied with
discussion of the nature of space and time, and of the continuity which
we must ascribe to them if the "continuous motion" on which the unbroken
life of the universe depends is to be real Aristotle knows nothing of
the modern questions whether space and time are "real" or only
"phenomenal," whether they are "objective" or "subjective. " Just as he
simply assumes that bodies are things that really exist, whether we
happen to perceive them or not, so he assumes that the space and time in
which they move are real features of a world that does not depend for
its existence on our perceiving it.

His treatment of space is singularly _naif_. He conceives it as a sort
of vessel, into which you can pour different liquids. Just as the same
pot may hold first wine and then water, so, if you can say, "there was
water here, but now there is air here," this implies the existence of a
receptacle which once held the water, but now holds the air. Hence a
jug or pot may be called a "place that can be carried about," and space
or place may be called "an immovable vessel. " Hence the "place" of a
thing may be defined as the boundary, or inner surface, of the body
which immediately surrounds the thing. It follows from this that there
can be no empty space. In the last resort, "absolute space" is the
actual surface of the outermost "heaven" which contains everything else
in itself but is not contained in any remoter body. Thus all things
whatever are "in" this "heaven. " But it is not itself "in" anything
else. In accord with the standing Greek identification of determinate
character with limitation, Aristotle holds that this outermost heaven
must be at a limited distance from us. Actual space is thus finite in
the sense that the volume of the universe could be expressed as a finite
number of cubic miles or yards, though, since it must be "continuous,"
it is infinitely divisible. However often you subdivide a length, an
area, or a volume, you will always be dividing it into lesser lengths,
&c. , which can once more be divided. You will never by division come to
"points," _i. e. _ mere positions without magnitude of divisibility.

The treatment of time is more thoughtful. Time is inseparably connected
with movement or change. We only perceive that time has elapsed when we
perceive that change has occurred. But time is not the same as change.
For change is of different and incommensurate kinds, change of place,
change of colour, &c. ; but to take up time is common to all these forms
of process. And time is not the same as motion. For there are
different rates of speed, but the very fact that we can compare these
different velocities implies that there are not different velocities of
_time_. Time then is that in terms of which we _measure_ motion, "the
number of motion in respect of before and after," _i. e. _ it is that by
which we estimate the _duration_ of processes. Thus _e. g. _ when we
speak of _two_ minutes, _two_ days, _two_ months as required for a
certain process to be completed, we are counting something. This
something is time. It does not seem to occur to Aristotle that this
definition implies that there are indivisible bits of time, though he
quite correctly states the incompatible proposition that time is "made
up of successive _nows_," _i. e. _ moments which have no duration at all,
and can no more be counted than the points on a straight line. He
recognises of course that the "continuity" of motion implies that of
time as well as of space. Since, however, "continuity" in his language
means the same thing as indefinite divisibility, it ought not to be
possible for him to regard time as "made up of _nows_"; time, like
linear extension, ought for him to be a "length of" something.

*The Continuous Motion and the "Spheres. "*--The continuous world-process
depends upon a continuous movement set up in the universe as a whole by
the presence of an everlasting and unchangeable "First Mover," God.
From the self-sameness of God, it follows that this most universal of
movements must be absolutely uniform. Of what precise kind can such a
movement be? As the source of the movement is one, and the object moved
is also one--viz. the compass of the "heaven," the movement of the
_primum mobile_ or "first moved"--the object immediately stimulated to
motion by God's presence to it, must be mechanically simple. Now
Aristotle, mistakenly, held that there are two forms of movement which
are simple and unanalysable, motion of translation along a straight
line, and motion of rotation round an axis. He is at pains to argue
that rectilinear motion, which we easily discover to be that
characteristic of bodies near the earth's surface when left to
themselves, cannot be the kind of movement which belongs to the "heaven"
as a whole. For continuous rectilinear movement in the same direction
could not go on for ever on his assumption that there is no space
outside the "heaven," which is itself at a finite distance from us. And
motion to and fro would not be unbroken, since Aristotle argues that
every time a moving body reached the end of its path, and the sense of
its movement was reversed, it would be for two consecutive moments in
the same place, and therefore at rest. Reversal of sense would imply a
discontinuity. Hence he decides that the primary unbroken movement must
be the rotation of the "first moved"--that is, the heaven containing the
fixed stars--round its axis. This is the only movement which could go
on for ever at a uniform rate and in the same sense. Starting with the
conviction that the earth is at rest in the centre of the universe, he
inevitably accounts for the alternation of day and night as the effect
of such a revolution of the whole universe round an axis passing through
the centre of the earth. The universe is thus thought of as bounded by
a spherical surface, on the concave side of which are the fixed stars,
which are therefore one and all at the same distance from us. This
sphere, under the immediate influence of God, revolves on its axis once
in twenty-four hours, and this period of revolution is absolutely
uniform. Next the apparently irregular paths of the "planets" known to
Aristotle (_i. e. _ the moon, Mercury, Venus, the sun, Mars, Jupiter,
Saturn) are resolved into combinations of similar uniform rotations,
each planet having as many "spheres" assigned to it as are requisite for
the analysis of its apparent path into perfectly circular elementary
motions. Altogether Aristotle holds that fifty-four such rotating
spheres are required over and above the "first moved" itself, whose
rotation is, of course, communicated to all the lesser "spheres"
included within it. As in the case of the "first moved," the uniform
unceasing rotation of each "sphere" is explained by the influence on it
of an unchanging immaterial "form," which is to its own "sphere" what
God is to the universe as a whole. In the Aristotelianism of the
mediaeval church these pure forms or intelligences which originate the
movements of the various planetary spheres are naturally identified with
angels. It is _e. g. _ to the angelic intelligences which "move" the
heaven of Venus, which comes third in order counting outward from the
earth, that Dante addresses his famous Canzone, _Voi ch' intendendo il
terzo del movete_. The mediaeval astronomy, however, differs in two
important respects from that of Aristotle himself. (1) The number of
"spheres" is different. Increasing knowledge of the complexity of the
paths of the planets showed that if their paths are to be analysed into
combinations of circular motions, fifty-four such rotations must be an
altogether inadequate number. Aristotle's method of analysis of the
heavenly movements was therefore combined with either or both of two
others originated by pure astronomers who sat loose to metaphysics. One
of these methods was to account for a planet's path by the introduction
of _epicycles_. The planet was thought of not as fixed at a given point
on its principal sphere, but as situated on the circumference of a
lesser sphere which has its centre at a fixed point of the principal
sphere and rotates around an axis passing through this centre. If need
were, this type of hypothesis could be further complicated by imagining
any number of such epicycles within epicycles. The other method was the
employment of "eccentrics," _i. e. _ circular movements which are
described not about the common centre of the earth and the universe, but
about some point in its neighbourhood. By combinations of epicycles and
eccentrics the mediaeval astronomers contrived to reduce the number of
principal spheres to _one_ for each planet, the arrangement we find in
Dante. (2) Also real or supposed astronomical perturbations unknown to
Aristotle led some mediaeval theorists to follow the scheme devised by
Alphonso the Wise of Castille, in which further spheres are inserted
between that of Saturn, the outermost planet, and the "first moved. " In
Dante, we have, excluding the "empyrean" or immovable heaven where God
and the blessed are, nine "spheres," one for each of the planets, one
for the fixed stars, and one for the "first moved," which is now
distinguished from the heaven of the stars. In Milton, who adopts the
"Alphonsine" scheme, we have further a sphere called the "second
movable" or "crystalline" introduced between the heaven of the fixed
stars and the "first moved," to account for the imaginary phenomenon of
"trepidation. "[#] In reading Dante, Shakespeare, and Milton, we have
always to remember that none of these reproduces the Aristotelian
doctrine of the "spheres" accurately; their astronomy is an amalgam of
Aristotle, Ptolemy, and Hipparchus.


[#] _Paradise Lost_, iii. 481.

"They pass the planets seven, and pass the fixed,
And that crystalline sphere whose balance weighs
The trepidation talked, and that first moved. "


So far, the doctrine of the fifty-five "spheres" might be no more than a
legitimate mathematical fiction, a convenient device for analysing the
complicated apparent movements of the heavenly bodies into circular
components. This was originally the part played by "spheres" in ancient
astronomical theory, and it is worth while to be quite clear about the
fact, as there is a mistaken impression widely current to-day that
Aristotle's astronomy is typical of Greek views in general. The truth
is that it is peculiar to himself. The origin of the theory was
Academic. Plato proposed to the Academy as a subject of inquiry, to
devise such a mathematical analysis of astronomical motions as will best
"save the appearances," _i. e. _ will most simply account for the apparent
paths of the planets. The analysis of these paths into resultants of
several rotations was offered as a solution by the astronomer Eudoxus of
Cnidus. So far, the "spheres," then, were a mere mathematical
hypothesis. What Aristotle did, and it is perhaps the most retrograde
step ever taken in the history of a science, was to convert the
mathematical hypothesis into physical fact. The "spheres" become with
him real bodies, and as none of the bodies we are familiar with exhibit
any tendency to rotate in circles when left to themselves, Aristotle was
forced to introduce into Physics the disastrous theory, which it was a
great part of Galileo's life-work to destroy, that the stuff of which
the spheres are made is a "fifth body," different from the "elements" of
which the bodies among which we live are made. Hence he makes an
absolute distinction between two kinds of matter, "celestial matter,"
the "fifth body," and "terrestrial" or "elementary" matter. The
fundamental difference is that "terrestrial" or "elementary" matter,
left to itself, follows a rectilinear path, "celestial" matter rotates,
but it is further inferred from the supposed absolute uniformity of the
celestial movements that "celestial matter" is simple, uncompounded,
incapable of change, and consequently that no new state of things can
ever arise in the heavens. The spheres and planets have always been and
will always be exactly as they are at the present moment. Mutability is
confined to the region of "terrestrial" or "elementary" matter, which
only extends as far as the orbit of the moon, the "lowest of the
celestial bodies," because it is only "terrestrial" things which are, as
we should say, chemical compounds. This is the doctrine which Galileo
has in mind when he dwells on such newly-discovered astronomical facts
as the existence of sun-spots and variable stars, and the signs of
irregularity presented by the moon's surface. The distinction is
peculiar to Aristotle. No one before him had ever thought of supposing
the heavenly bodies to be made of any materials other than those of
which "bodies terrestrial" are made. In the Academic attack on
Aristotle's science of which we have already spoken the two points
singled out for reprobation are (1) his rejection of the principle that
all moving bodies, left to themselves, follow a rectilinear path, and
(2) his denial that the heavenly bodies are made of the same "elements"
as everything else. (It may just be mentioned in passing that our word
_quintessence_ gets its sense from the supposed special "nobility" of
the incorruptible "fifth body. ")

*Terrestrial Bodies*. --As we have seen already, Aristotle was out of
sympathy with the tendency to regard the sensible differences between
bodies as consequences of more ultimate differences in the geometrical
structure of their particles. Hence his whole attitude towards the
problems of that branch of natural science which we call physics is
quite unlike any view to which we are accustomed. He reverts from the
mathematical lines of thought current in Plato's Academy to the type of
view more natural to the "plain man," and, like the earliest
sixth-century men of science, regards the _qualitative_ differences
which our senses apprehend as fundamental. Among these, particular
stress is laid on the difference in sensible temperature (the hot--the
cold), in saturation (the dry--the moist), and in density (the
dense--the rare). If we consider the first two of these oppositions, we
can make four binary combinations of the elementary "opposite"
characters, viz. hot and dry, hot and moist, cold and moist, cold and
dry. These combinations are regarded as corresponding respectively to
the sensible characteristics of the four bodies which Empedocles, the
father of Greek chemistry, had treated as the ultimate components of
everything. Fire is hot and dry, air hot and moist, water moist and
cold, earth cold and dry. This reflection shows us why Aristotle held
that the most rudimentary form in which "matter" ever actually exists is
that of one of these "elements. " Each of them has _one_ quality in
common with another, and it is in virtue of this that a portion of one
element can be assimilated by and transmuted into another, a process
which seems to the untutored eye to be constantly recurring in Nature.
We also observe that the order in which the "elements" appear, when so
arranged as to form a series in which each term has one quality in
common with each of its neighbours, is also that of their increasing
density. This would help to make the conception of their
transmutability all the more natural, as it suggests that the process
may be effected by steady condensation. We must remember carefully that
for Aristotle, who denies the possibility of a vacuum, as for the
mediaeval alchemists, condensation does not mean a mere diminution of the
distances between corpuscles which remain unchanged in character, but is
a process of real qualitative change in the body which undergoes it.
Incidentally we may remark that _all_ changes of quality are regarded by
Aristotle as stages in a continuous "movement" from one extreme of a
scale to another. For example, colours, with him as with Goethe, form a
series of which the "opposites" white and black are the end-points.
Every other colour is a combination of white and black according to a
definite proportion.

The Aristotelian doctrine of weight was one of the chief obstacles which
seventeenth-century science had to contend with in establishing correct
notions in dynamics. It is a curious feature of Greek science before
Aristotle that, though the facts connected with gravity were well known,
no one introduced the notion of weight to account for them. The
difference between heavy bodies and light bodies had been previously
treated as secondary for science. Plato's treatment of the matter is
typical of the best fourth-century science. We must not try to explain
why the heavier bodies tend to move towards the earth's surface by
saying that they have a "downward" motion; their motion is not downward
but "towards the centre" (the earth, though not fixed at the centre of
the universe, being nearer to it than the rest of the solar and sidereal
system). Plato then explains the tendency in virtue of which the
heavier bodies move towards the "centre" as an attraction of like for
like. The universal tendency is for smaller masses of "earth," "water,"
"air," "fire" to be attracted towards the great aggregations of the same
materials. This is far from being a satisfactory theory in the light of
facts which were not yet known to Plato, but it is on the right lines.
It starts from the conception of the facts of gravity as due to an
"attractive force" of some kind, and it has the great merit of bringing
the "sinking" of stones and the "rising" of vapours under the same
explanation.

Aristotle, though retaining the central idea that a body tends to move
towards the region where the great cosmic mass of the same kind is
congregated, introduced the entirely incompatible notion of an absolute
distinction of "up" and "down. " He identified the centre of the
universe with that of the earth, and looked on motion to this centre as
"downward. " This led him to make a distinction between "heavy" bodies,
which naturally tend to move "down," and "light" bodies, which tend to
move "up" away from the centre. The doctrine works out thus. The
heaviest elements tend to be massed together nearest the centre, the
lightest to be furthest from it. Each element thus has its "proper
place," that of water being immediately above earth, that of air next,
and that of fire furthest from the centre, and nearest to the regions
occupied by "celestial matter. " (Readers of Dante will recollect the
ascent from the Earthly Paradise through the "sphere of fire" with which
the _Paradiso_ opens. )

In its own "proper region" no body is heavy or light; as we should say
any fluid loses its weight when immersed in itself. When a portion of
an element is out of its own region and surrounded by the great cosmic
aggregate of another element, either of two cases may occur. The body
which is "out of its element" may be _below_ its proper place, in which
case it is "light" and tends to move perpendicularly upwards to its
place, or it may be _above_ its proper place, and then it is "heavy" and
tends to move perpendicularly "down" until it reaches its place. It was
this supposed real distinction between motion "up" and motion "down"
which made it so hard for the contemporaries of Galileo to understand
that an inflated bladder rises for the same reason that a stone sinks.

*Biology*. --Of Aristotle's biology reasons of space forbid us to say
much here. But a remark or two may be made about his theory of
reproduction, since it is constantly referred to in much modern
literature and has also played its part in theology. An interesting
point is the distinction between "perfect" and "imperfect" animals.
"Perfect" animals are those which can only be reproduced sexually.
Aristotle held, however, that there are some creatures, even among
vertebrates, which _may_ be produced by the vivifying effect of solar
heat on decomposing matter, without any parents at all. Thus
malobservation of the facts of putrefaction led to the belief that flies
and worms are engendered by heat from decaying bodies, and it was even
thought that frogs and mice are produced in the same way from
river-slime. In this process, the so-called "aequivocal generation,"
solar heat was conceived as the operative efficient cause which leads to
the realisation of an organic "form" in the decaying matter.

In sexual reproduction Aristotle regards the male parent as the agent or
efficient cause which contributes the element of form and organisation
to the offspring. The female parent supplies only the raw material of
the new creature, but she supplies the whole of this. No _material_ is
supplied by the male parent to the body of the offspring, a theory which
St. Thomas found useful in defending the dogma of the Virgin Birth.

*Psychology*. --Since the mind grows and develops, it comes under the
class of things which have a "source of motion internal to themselves,"
and psychology is therefore, for Aristotle, a branch of Physics. To
understand his treatment of psychological questions we need bear two
things in mind. (1) _Psyche_ or "soul" means in Greek more than
"consciousness" does to us. Consciousness is a relatively late and
highly developed manifestation of the principle which the Greeks call
"soul. " That principle shows itself not merely in consciousness but in
the whole process of nutrition and growth and the adaptation of motor
response to an external situation. Thus consciousness is a more
secondary feature of the "soul" in Greek philosophy than in most modern
thought, which has never ceased to be affected by Descartes' selection
of "thought" as the special characteristic of psychical life. In common
language the word _psyche_ is constantly used where we should say "life"
rather than "soul," and in Greek philosophy a work "on the _Psyche_"
means what we should call one on "the principle of life. "

(2) It is a consequence of this way of thinking of the "soul" that the
process of bodily and mental development is regarded by Aristotle as one
single continuous process. The growth of a man's intellect and
character by which he becomes a thinker and a citizen is a continuation
of the process by which his body is conceived and born and passes into
physical manhood. This comes out in the words of the definition of the
soul. "The soul is the first entelechy (or actual realisation) of a
natural organic body. " What this means is that the soul stands to the
living body as all form realised in matter does to the matter of which
it is the form, or that the soul is the "form" of the body. What the
"organic body" is to the embryo out of which it has grown, that soul is
to the body itself. As the embryo grows into the actual living body, so
the living body grows into a body exhibiting the actual directing
presence of mind. Aristotle illustrates the relation by the remark that
if the whole body was one vast eye, seeing would be its soul. As the
eye is a tool for seeing with, but a living tool which is part of
ourselves, so the body is a like tool or instrument for living with.
Hence we may say of the soul that it is the "end" of the body, the
activity to which the body is instrumental, as seeing is the "end" to
which the eye is instrumental. But we must note that the soul is called
only the "first" or initial "entelechy" of the body. The reason is that
the mere presence of the soul does not guarantee the full living of the
life to which our body is but the instrument. If we are to _live_ in
the fullest sense of the word, we must not merely "have" a soul; we
"have" it even in sleep, in ignorance, in folly. The soul itself needs
further to be educated and trained in intelligence and character, and to
exercise its intelligence and character efficiently on the problems of
thought and life. The mere "presence" of soul is only a first step in
the progress towards fullness of life. This is why Aristotle calls the
soul the _first_ entelechy of the living body. The full and final
entelechy is the life of intelligence and character actively
functioning.

From this conception of the soul's relation to the body we see that
Aristotle's "doctrine of body and mind" does not readily fall into line
with any of the typical theories of our time. He neither thinks of the
soul as a thing acting on the body and acted on by it, nor yet as a
series of "states of mind" concomitant with certain "states of body. "
From his point of view to ask whether soul and body interact, or whether
they exhibit "parallelism," would be much the same thing as to ask
whether life interacts with the body, or whether there is a
"parallelism" between vital processes and bodily processes. We must not
ask at all how the body and soul are united. They are one thing, as the
matter and the form of a copper globe are one. Thus they are in actual
fact inseparable. The soul is the soul of its body and the body the body
of its soul. We can only distinguish them by logical analysis, as we can
distinguish the copper from the sphericity in the copper globe.

*Grades of Psychical Life*. --If we consider the order of development, we
find that some vital activities make their appearance earlier than
others, and that it is a universal law that the more highly developed
activities always have the less highly developed as their basis and
precondition, though the less highly developed may exist apart from the
more highly developed. So we may arrange vital activities in general in
an ontogenetic order, the order in which they make their appearance in
the individual's development. Aristotle reckons three such stages, the
"nutritive," the "sensitive," and the "intelligent. " The lowest form in
which life shows itself at all, the level of minimum distinction between
the living and the lifeless, is the power to take in nutriment,
assimilate it, and grow. In vegetables the development is arrested at
this point. With the animals we reach the next highest level, that of
"sensitive" life.