I hold fast to this physical determinism, and accept a strictly mechanical conception of the functions of the nervous system. In my idea, the currents which pass through the cerebral mass follow each other without interruption, from the sensorial periphery to the motor periphery; it is they, and they alone, which excite the movements of the body by acting on the muscles. Parallelism recognises all these things, and I do likewise. Let us now see the advantages of this new system. First, it contains no paralogism, no logical or psychological error, since it does not advance the supposition that the mental differs by its nature from the physical phenomenon. We have discussed above the consequences of this error, They are here avoided. In the second place, it is explanatory, at least in a certain measure, since the formula we employ allows us to understand, better than by the principle of a simple juxtaposition, why certain nerve currents flow in the light of consciousness, while others are plunged into the darkness of unconsciousness. This law of consciousness, which Bain called the law of relativity, becomes, when embodied with my theory of the relations of the physical to the moral, an explanation of the distribution of consciousness through the actions of the brain. I ask myself whether the explanation I have devised ought to be literally preserved. Perhaps not. I have endeavoured less to present a ready-made solution than to indicate the direction in which we ought to look for one. The law of consciousness which I have used to explain the transformation of a nerve current into perception and images is only an empirical law produced by the generalisation of particular observations. Until now there has been, so far as I know, no attempt to ascertain whether this law of consciousness, notwithstanding the general nature which some authors incline to ascribe to it, might not explain itself by some more general facts, and might not fit, as a particular case, into a more comprehensive frame. To be brief, this is very possible. I have not troubled myself about it, and I have made a transcendental use of this empirical law; for I have impliedly supposed it to be a first principle, capable of accounting for the development of the consciousness, but itself incapable of explanation.