for which they make, and the
values they determine are all correlated with animal instincts and
external impressions. A desire is the inward sign of a physical
proclivity to act, an image in sense is the sign in most cases of some
material object in the environment and always, we may presume, of some
cerebral change. The brain seems to simmer like a caldron in which all
sorts of matters are perpetually transforming themselves into all sorts
of shapes. When this cerebral reorganisation is pertinent to the
external situation and renders the man, when he resumes action, more a
master of his world, the accompanying thought is said to be practical;
for it brings a consciousness of power and an earnest of success.

Cerebral processes are of course largely hypothetical. Theory suggests
their existence, and experience can verify that theory only in an
indirect and imperfect manner. The addition of a physical substratum to
all thinking is only a scientific expedient, a hypothesis expressing the
faith that nature is mechanically intelligible even beyond the reaches
of minute verification. The accompanying consciousness, on the other
hand, is something intimately felt by each man in his own person; it is
a portion of crude and immediate experience. That it accompanies changes
in his body and in the world is not an inference for him but a datum.
But when crude experience is somewhat refined and the soul, at first
mingled with every image, finds that it inhabits only her private body,
to whose fortunes hers are altogether wedded, we begin to imagine that
we know the cosmos at large better than the spirit; for beyond the
narrow limits of our own person only the material phase of things is
open to our observation. To add a mental phase to every part and motion
of the cosmos is then seen to be an audacious fancy. It violates all
empirical analogy, for the phenomenon which feeling accompanies in crude
experience is not mere material existence, but reactive organisation
and docility.

[Sidenote: Artifices involved in separating them.]

The limits set to observation, however, render the mental and material
spheres far from coincident, and even in a rough way mutually
supplementary, so that human reflection has fallen into a habit of
interlarding them. The world, instead of being a living body, a natural
system with moral functions, has seemed to be a bisectible hybrid, half
material and half mental, the clumsy conjunction of an automato