FRANKLAND.—On the Doctrine of Mind-Stuff. 218 
Our first step will show us how thoroughly interdependent all these con- 
ceptions are. Matter can only be defined as that which possesses inertia— 
as that which requires a force proportional to its amount (designated its 
mass) to effect a given change in its motion (either a change in velocity, or a 
change in direction, or both) in a given time. Force, again, can only be 
defined as that which causes a change in the velocity or direction of the 
motion of matter. It is tacitly assumed, though not often expressed, that 
the only thing which can cause such a change in velocity or direction is the 
co-existence of other matter. This amounts to saying that force is a rela- 
tion of co-existence between different portions of matter. But every relation 
of co-existence in the material or phenomenal world is a relation of mutual 
position in space. Hence force is a relation of mutual position between 
different portions of matter. Motion, in the kinetie, or dynamical, as 
opposed to the merely kinematical sense, is a change in the position of 
matter, and is completely determined when the mass of the moving body 
and the kinematical conditions of the case are given. The notion of energy 
does not require the introduction of any fundamentally new conception. 
Hence the phenomenal world is accurately described if we speak of it as a 
complex of motions, varying in infinite ways as regards mass on the one 
hand, and velocity and the other kinematical aspects on the other, tending 
severally to constancy in all these respects, but having a mutual action on one 
another, determined by their relations of co-existence, and, therefore, under- 
going perpetual transformations. Now mark the parallelism. The noumenal 
world, we have seen, may be described as a complex of feeling-elements, or 
Mind-Stuff units, having, just as motion has, extension in Time, varying in 
infinite ways as regards volume, intensity, and quality or timbre, having a 
mutual action on one another, determined by their mutual relations of 
co-existence, and undergoing perpetual transformations. Is this parallelism 
something more than a parallelism? Without attempting to justify it in this 
paper, I would hazard the conjecture that motion is Mind-Stuff, that volume 
of feeling is mass, and intensity of feeling velocity. Professor Clifford seems to 
have believed that motion and Mind-Stuff were identical, and indeed to have 
held the belief in a much more dogmatic form than I should be inclined to 
do; but the other two identifications are, as far as I am aware, quite new. 
The degree of light which cerebral physiology may be capable of throwing 
on the question must be estimated by abler minds than my own: but one 
implication of my hypothesis has struck me as favourable to it. If matter 
in motion be Mind-Stuff, it follows that if matter were ever at absolute rest, 
it would no longer correspond to any noumenal existence. It would become 
a pure abstraction—one term of a product, the other term of which was 
zero, Does not this appear in harmony with the hypothesis of Sir Wm. 
