ON THE PRINCIPLES

OF NATURAL SCIENCE

Book I.

1. The end and scope of natural philosophy.

Since the science of nature is in itself among those things which are desired, it contributes to the perfection and tranquility of the soul and the mind.

2. The distinction of nature.

Nature is in fact twofold: one of those things which are moved and can be moved; the other of those which are neither moved nor can be moved. Now, nothing is moved unless it be a body; wherefore the knowledge of that discipline which is subject to motion is entirely concerned with, and spent upon, the mobile body.

3. The principles of natural things.

The principles of natural and mobile things, whatsoever are generated and corrupted, are three: matter, form, and privation. And while matter and form are regarded as intrinsic and are the principal parts of the composite thing, privation is extrinsic. Moreover, of natural transmutations, such as generation and corruption, three principles are indeed numbered, and they are the same; but they are each required intrinsically. For it is necessary that, since the starting points and extremes of transmutations, or forms