ect of it, a question put to the motor activity and even the
beginning of a reply, there is no psychical event that does not imply
the entry into play of the cortical mechanisms. Everything seems,
therefore, to happen _as if_ consciousness sprang from the brain, and
_as if_ the detail of conscious activity were modeled on that of the
cerebral activity. In reality, consciousness does not spring from the
brain; but brain and consciousness correspond because equally they
measure, the one by the complexity of its structure and the other by the
intensity of its awareness, the quantity of _choice_ that the living
being has at its disposal.

It is precisely because a cerebral state expresses simply what there is
of nascent action in the corresponding psychical state, that the
psychical state tells us more than the cerebral state. The consciousness
of a living being, as we have tried to prove elsewhere, is inseparable
from its brain in the sense in which a sharp knife is inseparable from
its edge: the brain is the sharp edge by which consciousness cuts into
the compact tissue of events, but the brain is no more coextensive with
consciousness than the edge is with the knife. Thus, from the fact that
two brains, like that of the ape and that of the man, are very much
alike, we cannot conclude that the corresponding consciousnesses are
comparable or commensurable.

But the two brains may perhaps be less alike than we suppose. How can we
help being struck by the fact that, while man is capable of learning any
sort of exercise, of constructing any sort of object, in short of
acquiring any kind of motor habit whatsoever, the faculty of combining
new movements is strictly limited in the best-endowed animal, even in
the ape? The cerebral characteristic of man is there. The human brain is
made, like every brain, to set up motor mechanisms and to enable us to
choose among them, at any instant, the one we shall put in motion by the
pull of a trigger. But it differs from other brains in this, that the
number of mechanisms it can set up, and consequently the choice that it
gives as to which among them shall be released, is unlimited. Now, from
the limited to the unlimited there is all the distance between the
closed and the open. It is not a difference of degree, but of kind.

Radical therefore, also, is the difference between animal consciousness,
even the most intelligent, and human consciousness. For consciousness
corresponds exactly t