1. Above organic sensibility we find the stage of needs—that is to say, of purely vital or physiological tendencies with consciousness added. In man this period only exists at the beginning of life, and is translated by internal sensations (hunger, thirst, need of sleep, fatigue, etc.). It is constituted by a bundle of tendencies essentially physiological in character, and these tendencies have nothing added or external; they are life in action. Each anatomical element, each tissue, each organ has but one end, to exercise its activity; and the physiological individual is nothing but the convergent expression of all these tendencies. They may present themselves under a double form. In the one case they express a lack, a deficiency; the anatomical element, the tissue, the organism has need of something. In this form the tendency is imperious and irresistible; such is the hunger of the carnivorous animal, which swallows its prey alive. In the other case they translate an excess, a superfluity: such are, a gland which needs to secrete, a well-nourished animal which needs to move: this is the embryonic form of the luxurious emotions. All these needs have a point of convergence—the preservation of the individual; to use the current expression, we see in them the exercise of the _instinct of preservation_. On the subject of this instinct there have recently been discussions which seem to me sufficiently idle. Is the instinct of preservation primitive? is it derived? Some authors are for the first hypothesis; others (especially James and Sergi) lean towards the second. According to the point of view each of these two solutions is admissible and true. From the synthetic point of view the instinct of preservation is primordial, since it is nothing else but the resultant and sum of all the particular tendencies of each essential organ; it is only a collective formula. From the analytic point of view, it is secondary, since it presupposes all the particular tendencies into which it is dissolved, since each of its elements is simple, and since it adds nothing and is nothing but their translation into consciousness. One might ask in the same way if a sensation of sound is simple or compound, and here also, according to the point of view, the answer would vary. For consciousness the event is one, simple and irreducible; for objective analysis the event is compound, reducible to a definite number of vibrations. In the various regions of psychology we might find many problems of the same kind. The important point is to understand that the instinct of preservation is not an entity, but an abbreviated expression indicating a group of tendencies. 2. Emerging from the period of needs, which are thus reducible to tendencies of physiological order accompanied by physical pleasures or pains, we now enter the period of _primitive emotions_.