e, was presumably the originator of the idea. It will be
observed, too, that Anaxagoras alone is held responsible for the idea
that fishes respire air through their gills, "attracting" it from the
water. This certainly was one of the shrewdest physiological guesses
of any age, if it be regarded as a mere guess. With greater justice
we might refer to it as a profound deduction from the principle of the
uniformity of nature.

In making such a deduction, Anaxagoras was far in advance of his time as
illustrated by the fact that Aristotle makes the citation we have just
quoted merely to add that "such things are impossible," and to refute
these "impossible" ideas by means of metaphysical reasonings that seemed
demonstrative not merely to himself, but to many generations of his
followers.

We are told that Anaxagoras alleged that all animals were originally
generated out of moisture, heat, and earth particles. Just what opinion
he held concerning man's development we are not informed. Yet there is
one of his phrases which suggests--without, perhaps, quite proving--that
he was an evolutionist. This phrase asserts, with insight that is fairly
startling, that man is the most intelligent of animals because he has
hands. The man who could make that assertion must, it would seem, have
had in mind the idea of the development of intelligence through the use
of hands--an idea the full force of which was not evident to subsequent
generations of thinkers until the time of Darwin.

Physical Speculations

Anaxagoras is cited by Aristotle as believing that "plants are animals
and feel pleasure and pain, inferring this because they shed their
leaves and let them grow again." The idea is fanciful, yet it suggests
again a truly philosophical conception of the unity of nature. The man
who could conceive that idea was but little hampered by traditional
conceptions. He was exercising a rare combination of the rigidly
scientific spirit with the poetical imagination. He who possesses these
gifts is sure not to stop in his questionings of nature until he has
found some thinkable explanation of the character of matter itself.
Anaxagoras found such an explanation, and, as good luck would have it,
that explanation has been preserved. Let us examine his reasoning in
some detail. We have already referred to the claim alleged to have
been made by Anaxagoras that snow is not really white, but black. The
philosopher explained his paradox, we are told