Page:Philosophical Review Volume 31.djvu/489

No. 5.] (i.e., in a priori fashion) from this inaccurate notion, he involves himself in frequent error. The formation of individual living things is "Ideologically determined by the parental type which they are striving to realise. ... And he goes on to censure Empedocles for saying that many things in the animal body are due simply to mechanical causation; for example, the segmented structure of the backbone, which that philosopher attributes to continued doubling and twisting—the very same explanation, we believe, that would be given of it by a modern evolutionist." "To Aristotle the unbroken regularity of the celestial movements, which to us is the best proof of their purely mechanical nature, was, on the contrary, a proof that they were produced and directed by an absolutely reasonable purpose." According to Aristotle, "the reason why the heart, in man, inclines slightly towards the left side is that it may temper the greater coldness of that side. It is needless to observe that the left side of man is not colder than the right." " It is a fact that normally in turtles and exceptionally in elephants, horses, and oxen, there is an ossification of the septum of the heart. Aristotle saw or heard of one of these 'bones' in the hearts of a horse and an ox, and forthwith generalised the observation thus: 'The heart is destitute of bones except in horses and in a species of ox; these, however, in consequence of their size, have something bony as a support, just as we find throughout the whole body.'" Let it not be supposed, however, that Aristotle altogether neglects mechanical for final causes. Theoretically at least he has recognised and described the former as the "servants and instruments" of the latter. "Zeus," he says, "does not send rain that the plants may grow, but of necessity. For the rising exhalations