It is obvious that from this hypothesis as to the substantial identity of mind and motion, two important questions arise; and I feel that some reference to these questions is in present circumstances forced upon me, because they have both been considered in precisely the same connexion by one of the most powerful intellects that was ever sent out into the world by this University. I mean the late Professor Clifford. As my intimate and valued friend, I desire to mention his name in this place with all the affection, as well as with all the admiration, to which I well know it is so fully entitled; and if I appear to mention him only in order to disagree with him, this is only because I know equally well that in his large and magnanimous thought differences of philosophical opinion were never felt to weaken the bonds of friendship. In his well-known lecture on Body and Mind, Professor Clifford adopted the hypothesis of identity which we are now considering, and from it was led to the conclusion that if in the case of cerebral processes motion is one with mind, the same must be true of motion wherever it occurs; or, as he expressed it subsequently, the whole universe must be made of mind-stuff. But in his view, although matter in motion presents what may be termed the raw material of mind, it is only in the highly elaborated constitution of the human brain that this raw material is sufficiently wrought up to yield a self-conscious personality. Hence the dissolution of a human brain implies the dissolution of a human mind; and hence also the universe, although entirely composed of mind-stuff, is itself mindless. Now, all I have to say about these two deductions is this--they do not necessarily follow from the theory which is before us. In holding that the mind of man perishes with his body, and that above the mind of man there is no other, Clifford may have been right, or may have been wrong. I am not here to discuss at length any questions of such supreme importance. But I feel that I am here to insist upon the one point which is immediately connected with my subject; and this is, that whether or not Clifford was right in his conclusions, these conclusions certainly did not follow by way of any logical sequence from his premises. Because within the limits of human experience mind is only known as associated with brain, it clearly does not follow that mind cannot exist in any other mode. It does not even follow that any probability upon this matter can be thus established. The basis of analogy on which Clifford sought to rear an inference of cosmical extent, was restricted to the one instance of mind as known upon one planet; and, therefore, it is hard to imagine a more precarious use of that precarious method which is called by logicians simple enumeration. Indeed, even for what it is worth, the inference may be pointed with quite as much effect in precisely the opposite direction. For we have