The materials for this investigation can only be sought in the psychology of animals and in that of children. The first will give us but little help. No doubt special and authoritative treatises enumerate the emotions of animals, but without any distinction between the simple and the compound, and with no precise indication as to the order of their appearance. It is not the same with infantile psychology; the numerous studies published on this subject during the last thirty years have rendered possible an attempt which could not be made before. The question is then to determine in accordance with facts the order in which the emotions appear, only taking into account those which seem primitive—that is to say, not reducible to other emotions. I limit myself to their simple enumeration, with an indication of their chief characters; each of them will be the object of a special study in the second part of this book. 1. Fear is the first in date, according to unanimous observations. Preyer finds that it is manifested from the second day. At the same time the fact which he records seems to me to agree with surprise rather than with fear properly so called. In any case, according to the same author, it is easy to note it after twenty-four hours. Darwin thought he could only observe it at the end of four months, Perez at two months. The last is inclined to believe that this emotion is first aroused by auditory sensations, and then by visual sensations. The precocity of its appearance has been attributed to hereditary transmission, an assertion which we shall have to examine. 2. After the defensive emotion, the offensive emotion appears in the form of anger. Perez notes it between two and three months; Preyer and Darwin at ten months; they mean real anger, marked by the contraction of the eyebrows and other clear symptoms (to throw itself about, crying, etc.). Naturally the dates indicated for each emotion are not rigorously fixed; they must vary according to the child’s temperament and circumstances. 3. Then comes affection. Some authors use the word sympathy, which seems to me too vague. It shows itself by its fundamental method of expression, the movement of attraction, the seeking for contact. Darwin, who has well described it, remarks that it probably appears very early in life, judging by the infant’s smile, in the second month, but that he had no clear proof that the child recognised any one before the fourth month; at the fifth month he showed a wish to go towards his nurse, but only at twelve months did he show affection spontaneously and by plain gestures. Darwin adds that sympathy (?) was manifested exactly at ten months, eleven days, when the child’s nurse pretended to cry.[7] According to Perez, it appears towards ten months.[8] It is from this source that complex forms of great importance must later on be derived—the social and moral emotions. ----- Footnote 7: Darwin, “Biographical Sketch of an Infant,” _Mind_, ii. p. 285.