In order to give to this question a clear and concrete form, let us take primitive man, as reconstructed by the anthropologists, not without much hypothesis and conjecture. Whether he were the ferocious wild beast described by some, or a puny, feeble, naked being, chipping his first weapons among the rolled flints of a river-bed, keeping up with difficulty his famished life from day to day, and finding a precarious shelter from incessant dangers in the hollows of the rocks, it is in any case certain that he made originally but a poor figure on the surface of the globe. How has he progressed from primitive cannibalism to his present moral and social culture? from the bestial sexual act to chivalrous love? from coarse fetichism to religious metaphysics or mysticism? from the rude drawings of the Neolithic age to the refinements of the æsthetic sentiment? from a narrow and limited curiosity to a disinterested enthusiasm for science? How has the passage been accomplished from one extreme to the other? It is clear that a new form of feeling cannot arise by spontaneous generation; it can only be the work of a transformation, of a physiological development. How has this happened? What causes have brought about this metamorphosis? The principal, essential, fundamental cause is intellectual development. Another cause, adduced by many writers, but more doubtful and more limited in its action, is transmission by heredity. 1. In spite of its importance, the first cause need not detain us long, since it can only be presented, for the moment, under the form of vague generalities. Its action consists in the ascending progression which rises from the inferior forms of knowledge (sensations and perceptions) to concrete representations, then to abstract representations (generic images), then to the medium and superior forms of abstraction, and involves in its movement concomitant modifications of affective life produced by reaction. Primitive man, like the child and the animal, is at first only a bundle of wants, tendencies, instincts which, when not simply unconscious, are connected with external or internal tendencies. The instinct of self-preservation, a synthetic formula expressing a group of subordinate and convergent instincts, adjusts itself differently according to circumstances—sometimes defensive, sometimes offensive. It is only determined by the successive ends which it has to attain, just as the muscular force of my arm may be equally well employed in raising a weight, in firing a gun, in striking a blow, or in caressing. The intellectual element, whatever it may be, is always the determining principle; never, alone and by itself, the spring of action. The process always follows the same course, and remains identical from start to finish; it passes from the simple into the complex, as we shall see in discussing each separate emotion. The child who feels acutely the possession of a toy, or the deprivation of it, is not affected by the beauty of a