upon them as acting by "living
force as much as the sensitive mimosa does when it contracts its leaves
at touch." But living force is what we are trying to differentiate from
mechanical force, and what do we gain by confounding the two? We can
only look upon a living body as a machine by forming new conceptions of
a machine--a machine utterly unmechanical, which is a contradiction of
terms.

A man may expend the same kind of force in thinking that he expends in
chopping his wood, but that fact does not put the two kinds of activity
on the same level. There is no question but that the food consumed is
the source of the energy in both cases, but in the one the energy is
muscular, and in the other it is nervous. When we speak of mental or
spiritual force, we have as distinct a conception as when we speak of
physical force. It requires physical force to produce the effect that we
call mental force, though how the one can result in the other is past
understanding. The law of the correlation and conservation of energy
requires that what goes into the body as physical force must come out in
some form of physical force--heat, light, electricity, and so forth.

Science cannot trace force into the mental realm and connect it with our
states of consciousness. It loses track of it so completely that men
like Tyndall and Huxley and Spencer pause before it as an inscrutable
mystery, while John Fiske helps himself out with the conception of the
soul as quite independent of the body, standing related to it as the
musician is related to his instrument. This idea is the key to Fiske's
proof of the immortality of the soul. Finding himself face to face with
an insoluble mystery, he cuts the knot, or rather, clears the chasm, by
this extra-scientific leap. Since the soul, as we know it, is
inseparably bound up with physical conditions, it seems to me that a
more rational explanation of the phenomenon of mentality is the
conception that the physical force and substance that we use up in a
mental effort or emotional experience gives rise, through some unknown
kind of molecular activity, to something which is analogous to the
electric current in a live wire, and which traverses the nerves and
results in our changing states of consciousness. This is the mechanistic
explanation of mind, consciousness, etc., but it is the only one, or
kind of one, that lends itself to scientific interpretation. Life,
spirit, consciousness, may be a mode of moti