f the brain, the corresponding thought
or feeling might be inferred: or, given the thought or feeling, the
corresponding state of the brain might be inferred. But how inferred?
It would be at bottom not a case of logical inference at all, but of
empirical association. You may reply, that many of the inferences of
science are of this character--the inference, for example, that an
electric current, of a given direction, will deflect a magnetic needle
in a definite way. But the cases differ in this, that the passage
from the current to the needle, if not demonstrable, is conceivable,
and that we entertain no doubt as to the final mechanical solution of
the problem. But the passage from the physics of the brain to the
corresponding facts of consciousness is inconceivable as a result of
mechanics. Granted that a definite thought, and a definite molecular
action in the brain, occur simultaneously; we do not possess the
intellectual organ, nor apparently any rudiment of the organ, which
would enable us to pass, by a process of reasoning, from the one to
the other. They appear together, but we do not know why. Were our
minds and senses so expanded, strengthened, and illuminated, as to
enable us to see and feel the very molecules of the brain; were we
capable of following all their motions, all their groupings, all their
electric discharges, if such there be; and were we intimately
acquainted with the corresponding states of thought and feeling, we
should be as far as ever from the solution of the problem, 'How are
these physical processes connected with the facts of consciousness?'
The chasm between the two classes of phenomena would still remain
intellectually impassable. Let the consciousness of love, for
example, be associated with a right-handed spiral motion of the
molecules of the brain, and the consciousness of hate with a
left-handed spiral motion. We should then know, when we love, that
the motion is in one direction, and, when we hate, that the motion is
in the other; but the WHY?' would remain as unanswerable as before.

In affirming that the growth of the body is mechanical, and that
thought, as exercised by us, has its correlative in the physics of the
brain, I think the position of the 'Materialist' is stated, as far as
that position is a tenable one. I think the materialist will be able
finally to maintain this position against all attacks; but I do not
think, in the present condition of the human mind,