No More Learning

But lest
Haply thou holdest that those images
Which come from objects are the sole that flit,
Others indeed there be of own accord
Begot, self-formed in earth's aery skies,
Which, moulded to innumerable shapes,
Are borne aloft, and, fluid as they are,
Cease not to change           and to turn
Into new outlines of all sorts of forms;
As we behold the clouds grow thick on high
And smirch the serene vision of the world,
Stroking the air with motions.