hanges of temperature, a watch is exhibiting the
mechanical aspect of volition. And, similarly, it is perhaps possible to
conceive that the principles of mechanism might be more and more
extended in their effects, until, in so marvellously perfected a
structure as the human brain, all the voluntary movements of the body
might be originated in the same mechanical manner as are the
compensating movements of a watch; for this, indeed, as we have seen, is
no more than happens in the case of all the nerve-centres other than the
cerebral hemispheres. If this were so, motion would be producing nothing
but motion, and upon the subject of brain-action there would be nothing
further to say. Without consciousness I should be delivering this
lecture; without consciousness you would be hearing it; and all the busy
brains in this University would be conducting their researches, or
preparing for their examinations, mindlessly. Strange as such a state
of things might be, still motion would be producing nothing but motion;
and, therefore, if there were any mind to contemplate the facts, it
would encounter no philosophical paradox: it would merely have to
conclude that such were the astonishing possibilities of mechanism. But,
as the facts actually stand, we find that this is not the case. We find,
indeed, that up to a certain level of complexity mechanism alone is able
to perform all the compensations or adjustments which are performed by
the animal body; but we also find that beyond this level such
compensations or adjustments are never performed without the
intervention of consciousness. Therefore, the theory of automatism has
to meet the unanswerable question--How is it that in the machinery of
the brain motion produces this something which is not motion? Science
has now definitely proved the correlation of all the forces; and this
means that if any kind of motion could produce anything else that is not
motion, it would be producing that which science would be bound to
regard as in the strictest sense of the word a miracle. Therefore, if we
are to take our stand upon science--and this is what materialism
professes to do--we are logically bound to conclude, not merely that the
evidence of causation from body to mind is not so cogent as that of
causation in any other case, but that in this particular case causation
may be proved, again in the strictest sense of the term, a physical
impossibility.

To adduce only one other consideration