nsciousness?
The chasm between the two classes of phenomena would still remain
intellectually impassable[7].'

Next, in all cases of recognized causation there is a perceived
_equivalency_ between cause and effect, such equivalency belonging to
the very essence of that in which we conceive causation to consist. But
as between matter and motion on the one side, and feeling and thought on
the other, there can be no such equivalency conceivable. That no such
equivalency is conceivable may be rendered apparent on grounds of
Materialism itself. For Materialism is bound to accept the fundamental
doctrine of modern physics--that, viz. as to the conservation of
energy--and therefore it becomes evident that unless we assimilate
thought with energy, there is no possibility of a causal relation, or a
relation of equivalency, as obtaining between the one and the other.
For however little we may know about brain-dynamics, materialists, at
least, must take it for granted that in every process of cerebration the
matter and force concerned are indestructible quantities, and therefore
that all their possible equations are fully satisfied, could we but
follow them out. Howsoever complex we may suppose the flux and reflux of
forces to be within the structure of a living brain, it is no more
possible for any one of the forces concerned to escape from brain to
mind, than it would be for such an escape to occur in a steam-engine or
a watch; the doctrine of the conservation of energy forms an insuperable
bar to the supposition that any equation in the region of physics can be
left unsatisfied, in order to pass over and satisfy some other equation
in the region of psychics.

Of course in saying this I am aware that some of the more clear-sighted
of the materialists have plainly perceived this difficulty in all its
magnitude, and so have felt that unless it can be met, any theory of
Materialism must necessarily contain a radical contradiction of
principles. Some few materialists have therefore sought to meet the
difficulty in the only way it can be met, viz. by boldly asserting the
possibility of thought and energy being transmutable. On this view
thought becomes a mode of motion, and takes its rank among the forces as
identical in nature with heat, light, electricity, and the rest. But
this view is also inherently impossible. For suppose, as a matter of
argument, that physiologists should discover a mechanical equivalent of
thought