"The reflexes of pains which, in later life, show themselves in the acutest manner, are those best developed in early life. Gunzmer’s observations on about sixty infants showed him that, during the first few days, they are almost insensible, and during the first week, very slightly sensitive, to the pricking of a needle. “New-born infants have been, in the course of their first day, pricked with fine needles, on the nose, the upper lip, and the hand, deeply enough to draw a drop of blood; yet the child manifested no symptom of consciousness, and did not start once.”—Preyer, _Seele des Kindes_, pp. 177, 193. Leaving aside this question of origin, it is impossible to close the study of pleasure and pain without a summary recapitulation of the general theories forming the philosophy of our subject. These may be classified under two heads: the _how_ and the _why_; what are the conditions of existence of pleasure and pain? and what is their utility? I. On the first point there has been, from antiquity to the present day, an almost universal and very rare agreement between different schools: pleasure has, as its condition, an increased, pain a diminished activity. I employ this vague formula designedly, because it covers all special formulas. Of these it would be idle to enumerate even the chief. At bottom, in language varying according to the era and the doctrine, all authors say the same thing, employing, according to their cast of intellect, a metaphysical, physical (Léon Dumont), physiological, or psychological formula. The intellectualists themselves agree with the others; considering sensibility as a confused form of intelligence, they say that pleasure is a confused judgment of perfection, and pain a confused judgment of imperfection. In short, if each formula is stripped of the variations adapting it to the particular philosophy of each author, there is a common residue, which, in all alike, is the essential. The history of these variations on the same theme would be monotonous and unprofitable; it is as well, however, to note that, as our own century advances, the theoretic conception of the ancients tends to grow more precise, to rely more on the support of experience and be justified thereby. We have already seen the two formulas—augmentation, diminution—taking definite shape, showing themselves in the objective and observable changes of nutrition, of the secretions, the movements, the circulation, and the breathing.