To revert to primordial feeling is an exercise in mental disintegration, not a feat of science. We might, indeed, as in animal psychology, retrace the situations in which instinct and sense seem first to appear and write, as it were, a genealogy of reason based on circumstantial evidence. Reason was born, as it has since discovered, into a world already wonderfully organised, in which it found its precursor in what is called life, its seat in an animal body of unusual plasticity, and its function in rendering that body’s volatile instincts and sensations harmonious with one another and with the outer world on which they depend. It did not arise until the will or conscious stress, by which any modification of living bodies’ inertia seems to be accompanied, began to respond to represented objects, and to maintain that inertia not absolutely by resistance but only relatively and indirectly through labour. Reason has thus supervened at the last stage of an adaptation which had long been carried on by irrational and even unconscious processes. Nature preceded, with all that fixation of impulses and conditions which gives reason its tasks and its _point-d’appui_. Nevertheless, such a matrix or cradle for reason belongs only externally to its life. The description of conditions involves their previous discovery and a historian equipped with many data and many analogies of thought. Such scientific resources are absent in those first moments of rational living which we here wish to recall; the first chapter in reason’s memoirs would no more entail the description of its real environment than the first chapter in human history would include true accounts of astronomy, psychology, and animal evolution. [Sidenote: The flux first.]