Mr. Sidgwick points out that, when treating of the “Data of Psychology,” I have said (in § 56) that, though we reach inferentially “the belief that mind and nervous action are the subjective and objective faces of the same thing, we remain utterly incapable of seeing, and even of imagining, how the two are related” (I quote the passage more fully than he does). He then goes on to show that in the “Special Synthesis,” where I have sketched the evolution of Intelligence under its objective aspect, as displayed in the processes by which beings of various grades adjust themselves to surrounding actions, I “speak as if” we could see how consciousness “naturally arises at a particular stage” of nervous action. The chapter he here refers to is one describing that “differentiation of the psychical from the physical life” which accompanies advancing organization, and more especially advancing development of the nervous system. In it I have shown {240} that, while the changes constituting physical life continue to be characterized by the _simultaneity_ with which all kinds of them go on throughout the organism, the changes constituting psychical life, arising as the nervous system develops, become gradually more distinguished by their _seriality_. And I have said that as nervous integration advances, “there must result an unbroken series of these changes—there must arise a consciousness.” Now I admit that here is an apparent inconsistency. I ought to have said that “there must result an unbroken series of these changes,” which, taking place in the nervous system of a highly-organized creature, gives coherence to its conduct; and along with which we assume a consciousness, because consciousness goes along with coherent conduct in ourselves. If Mr. Sidgwick will substitute this statement for the statement as it stands, he will see that the arguments and conclusions remain intact. A survey of the chapter as a whole, proves that its aim is not in the least to explain how nervous changes, considered as waves of molecular motion, become the feelings constituting consciousness; but that, contemplating the facts objectively in living creatures at large, it points out the cardinal distinction between vital actions in general, and those particular vital actions which, in a creature displaying them, lead us to speak of it as intelligent. It is shown that the rise of such actions becomes marked in proportion as the changes taking place in the part called the nervous system, are made more and more distinctly serial, by union in a supreme centre of co-ordination. The introduction of the word consciousness, arises in the effort to show what fundamental character there is in these particular physiological changes which is _parallel to_ a fundamental character in the psychological changes.