, so that we might estimate the value of a calculation in thermal
units, or the 'labour of love' in foot-pounds: still we should not be
out of our difficulties; we should only have to cut a twist of flax to
find a lock of iron. For by thus assimilating thought with energy, we
should in no wise have explained the fundamental antithesis between
subject and object. The fact would remain, if possible, more
unaccountable than ever, that mind should present absolutely no point of
real analogy with motion. Involved with the essential idea of motion is
the idea of extension; suppress the latter and the former must
necessarily vanish, for motion only means transition in space of
something itself extended. But thought, as far as we can possibly know
it, is known and distinguished by the very peculiarity of not having
extension. Therefore, even if we were to find a mechanical equivalent of
thought, thought would still not be proved a mode of motion. On the
contrary, what would be proved would be that, in becoming transformed
into thought, energy had ceased to be energy; in passing out of its
relation to space it would cease to exist as energy, and if it again
passed into that relation it would only be by starting _de novo_ on a
new course of history. Therefore the proof that thought has a mechanical
equivalent would simply amount to the proof, not that thought _is_
energy, but that thought _destroys_ energy. And if Materialism were to
prove this, Materialism would commit suicide. For if once it were
proved that the relation of energy to thought is such that thought is
able to absorb or temporarily to annihilate energy, the whole argument
of Materialism would be inverted, and whatever evidence there is of
causation as between mind and matter would become available in all its
force on the side of Spiritualism. This seems plain, for if it even were
conceivable--which most distinctly it is not--that a motor could ever
become a motive, and so pass from the sphere of dynamics into the sphere
of consciousness, the fact would go to prove, not that the motor was the
cause of the motive, but rather that the motive was the cause of
destroying the motor; so that at that point the otherwise unbroken chain
of physical sequences was interrupted by the motive striking in upon it,
and in virtue of the mysterious power supposed to have been proved by
physiology, cancelling the motor, so allowing the nerve-centre to act as
determined by the motive.