Page:Aristotelous peri psuxes.djvu/30

20 crushes by its contraction those forms of atoms which, from never being at rest, give motion, and that compensation is afforded for their exit by the entrance of other like forms, during inspiration; and that these forms, while entering, resist the contracting and solidifying power, and preclude the expulsion of all the atoms which are essential to life. They further maintain that animals can live only so long as they can support this process. The opinion adopted by the Pythagoreans seems to be to the same purport—for some of them have maintained that Vital Principle is the motes in the air, and others that it is that which gives motion to the motes; and it has thus been said of those corpuscles, because of their appearing to be constantly moving, although the air may be quite still.

To the same point do they also come who say that the Vital Principle is self-motive ; for all these philosophers seem to have assumed that motion is the most characteristic property of the Vital Principle ; and that, while all other things are moved by it, it is self-moved, and the more so, as they do not see any motor which is not self-moved.

Anaxagoras, in like manner, says that the Vital Principle is a motive force, and the same opinion may be attributed to any one who, with him, may have maintained that the mind has given motion to the universe; and yet his opinion is not altogether in