and
deadened or even annihilated by narcotics? Is it not entirely suspended
in healthy sleep? Will not a man of genius become an imbecile if his
brain softens? Will not a philosopher rave like a drunken fishfag if he
suffers from brain inflammation? Is not thought most vigorous when
the brain is mature? And is it not weakest in the first and second
childishness of youth and old age?

The dependence of thought on the brain is so obvious, it is so
demonstrable by the logical methods of difference and concomitant
variations, that whoever disputes it, or only allows it "to a certain
extent," is bound to assign another definite cause. A _definite_
cause, we say; not a fanciful or speculative one, which is perfectly
hypothetical.

Sir G. G. Stokes does not do this. He tries to make good his reservation
by a negative criticism of "the materialistic hypothesis." He takes the
case of a man who, while going up a ladder and speaking, was knocked
on the head by a falling brickbat. For two days he was unconscious, and
"when he came to, he completed the sentence that he had been speaking
when he was struck." Now, at first sight, this seems a strong
confirmation of "the materialistic hypothesis." A shock to the brain
stopped its action and suspended consciousness. Automatic animal
functions went on, but there was no perception, thought, or feeling.

When the effects of the shock wore off the brain resumed its action, and
began at the very point where it left off. But this last circumstance
is seized by Sir G. G. Stokes as "a difficulty." _Some_ change must have
gone on, he says, during the two days the man lay unconscious; there
must have been _some_ waste of tissues, _some_ change in the brain; yet
"there is no trace of this change in the joining together of the thought
after the interval of unconsciousness with the thought before."

Our reply is a simple one. In the first place, Sir G. G. Stokes is
making much of a single fact, which he has not weighed, in despite of a
host of other facts, not in the least questionable, and all pointing in
one direction. In the second place, he does not tell us _what_ change
went on in the man's brain. May it not have been, at least with respect
to the cerebrum, quite infinitesimal? In the third place, Sir G.
G. Stokes should be aware that all brain changes do not affect
consciousness, even in the normal state. Lastly, consciousness depends
upon perception; and if all the avenues of sensation w