istence.]

When Democritus proclaimed the sovereignty of mechanism, he did so in
the oracular fashion proper to an ancient sage. He found it no harder to
apply his atomic theory to the mind and to the gods than to solids and
fluids. It sufficed to conceive that such an explanation might be
possible, and to illustrate the theory by a few scattered facts and
trenchant hypotheses. When Descartes, after twenty centuries of verbal
physics, reintroduced mechanism into philosophy, he made a striking
modification in its claims. He divided existence into two independent
regions, and it was only in one, in the realm of extended things, that
mechanism was expected to prevail. Mental facts, which he approached
from the side of abstracted reflection and Platonic ideas, seemed to him
obviously non-extended, even when they represented extension; and with
them mechanism could have nothing to do. Descartes had recovered in the
science of mechanics a firm nucleus for physical theory, a stronghold
from which it had become impossible to dislodge scientific methods.
There, at any rate, form, mass, distance, and other mathematical
relations governed the transformation of things. Yet the very clearness
and exhaustiveness of this mechanical method, as applied to gross masses
in motion, made it seem essentially inapplicable to anything else.
Descartes was far too radical and incisive a thinker, however, not to
feel that it must apply throughout nature. Imaginative difficulties due
to the complexity of animal bodies could not cloud his rational insight.
Animal bodies, then, were mere machines, cleancut and cold engines like
so many anatomical manikins. They explained themselves and all their
operations, talking and building temples being just as truly a matter of
physics as the revolution of the sky. But the soul had dropped out, and
Descartes was the last man to ignore the soul. There had dropped out
also the secondary qualities of matter, all those qualities, namely,
which are negligible in mechanical calculations. Mechanism was in truth
far from universal; all mental facts and half the properties of matter,
as matter is revealed to man, came into being without asking leave; they
were interlopers in the intelligible universe. Indeed, Descartes was
willing to admit that these inexplicable bystanders might sometimes put
their finger in the pie, and stir the material world judiciously so as
to give it a new direction, although without adding to it