Atkinson[188] seems to have been the first to recognize that these conditions of the Darwinian primal horde would in practice bring about the exogamy of the young men. Each one of those driven away could found a similar horde in which, thanks to jealousy of the chief, the same prohibition as to sexual intercourse obtained, and in the course of time these conditions would have brought about the rule which is now known as law: no sexual intercourse with the members of the horde. After the advent of totemism the rule would have changed into a different form: no sexual intercourse within the totem. Andrew Lang[189] declared himself in agreement with this explanation of exogamy. But in the same book he advocates the other theory of Durkheim which explains exogamy as a consequence of the totem laws. It is not altogether easy to combine the two interpretations; in the first case exogamy would have existed before totemism; in the second case it would be a consequence of it[190]. 3 Into this darkness psychoanalytic experience throws one single ray of light. The relation of the child to animals has much in common with that of primitive man. The child does not yet show any trace of the pride which afterwards moves the adult civilized man to set a sharp dividing line between his own nature and that of all other animals. The child unhesitatingly attributes full equality to animals; he probably feels himself more closely related to the animal than to the undoubtedly mysterious adult, in the freedom with which he acknowledges his needs. Not infrequently a curious disturbance manifests itself in this excellent understanding between child and animal. The child suddenly begins to fear a certain animal species and to protect himself against seeing or touching any individual of this species. There results the clinical picture of _animal phobia_, which is one of the most frequent among the psychoneurotic diseases of this age and perhaps the earliest form of such an ailment. The phobia is as a rule in regard to animals for which the child has until then shown the liveliest interest and has nothing to do with the individual animal. In cities the choice of animals which can become the object of phobia is not great. They are horses, dogs, cats, more seldom birds, and strikingly often very small animals like bugs and butterflies. Sometimes animals which are known to the child only from picture books and fairy stories become objects of the senseless and inordinate anxiety which is manifested with these phobias; it is seldom possible to learn the manner in which such an unusual choice of anxiety has been brought about. I am indebted to Dr Karl Abraham for the report of a case in which the child itself explained its fear of wasps by saying that the colour and the stripes of the body of the wasp had made it think of the tiger of which, from all that it had heard, it might well be afraid.