The same principle may be extended in a different direction if we substitute for knowledge, in its narrower significance, the more general conception of associated feeling. We shall then see that belief, habit, emotion, and instinct are only different stages of the same process—the process by which experience is organised and made subservient to vital activity. The simplest reflex and the highest intellectual conviction are alike based on sensori-motor mechanism, and, so far, differ only through the relative complexity and instability of the nervous connexions involved. Knowledge is life in the making, and when it fails to control practice fails only by coming into conflict with passion—that is to say, with the consolidated results of an earlier experience. Physiology offers another analogy to the Socratic method which must not be overlooked. Socrates recommended the formation of definite conceptions because, among other advantages, they facilitated the diffusion of useful knowledge. So, also, the organised associations of feelings are not only serviceable to individuals, but may be transmitted to offspring with a regularity proportioned to their definiteness. How naturally these deductions follow from the doctrine under consideration, is evident from their having been, to a certain extent, already drawn by Plato. His plan for the systematic education of feeling under scientific supervision answers to the first; his plan for breeding an improved race of citizens by placing marriage under State control answers to the second. Yet it is doubtful whether Plato’s predecessor would have sanctioned any scheme tending to substitute an external compulsion, whether felt or not, for freedom and individual initiative, and a blind instinct for the self-consciousness which can give an account of its procedure at every step. He would bring us back from social physics and physiology to psychology, and from psychology to dialectic philosophy. IV.