other centre
to the circle but the empirical study of evolution. It is only in seeing
consciousness run through matter, lose itself there and find itself
there again, divide and reconstitute itself, that we shall form an idea
of the mutual opposition of the two terms, as also, perhaps, of their
common origin. But, on the other hand, by dwelling on this opposition of
the two elements and on this identity of origin, perhaps we shall bring
out more clearly the meaning of evolution itself.

Such will be the aim of our next chapter. But the facts that we have
just noticed must have already suggested to us the idea that life is
connected either with consciousness or with something that resembles it.

Throughout the whole extent of the animal kingdom, we have said,
consciousness seems proportionate to the living being's power of choice.
It lights up the zone of potentialities that surrounds the act. It fills
the interval between what is done and what might be done. Looked at from
without, we may regard it as a simple aid to action, a light that action
kindles, a momentary spark flying up from the friction of real action
against possible actions. But we must also point out that things would
go on in just the same way if consciousness, instead of being the
effect, were the cause. We might suppose that consciousness, even in the
most rudimentary animal, covers by right an enormous field, but is
compressed in fact in a kind of vise: each advance of the nervous
centres, by giving the organism a choice between a larger number of
actions, calls forth the potentialities that are capable of surrounding
the real, thus opening the vise wider and allowing consciousness to pass
more freely. In this second hypothesis, as in the first, consciousness
is still the instrument of action; but it is even more true to say that
action is the instrument of consciousness; for the complicating of
action with action, and the opposing of action to action, are for the
imprisoned consciousness the only possible means to set itself free.
How, then, shall we choose between the two hypotheses? If the first is
true, consciousness must express exactly, at each instant, the state of
the brain; there is strict parallelism (so far as intelligible) between
the psychical and the cerebral state. On the second hypothesis, on the
contrary, there is indeed solidarity and interdependence between the
brain and consciousness, but not parallelism: the more complicated the