It is, moreover, clear that the action of the thumbsucking child is determined by the fact that it seeks a pleasure which has already been experienced and is now remembered. Through the rhythmic sucking on a portion of the skin or mucous membrane it finds the gratification in the simplest way. It is also easy to conjecture on what occasions the child first experienced this pleasure which it now strives to renew. The first and most important activity in the child's life, the sucking from the mother's breast (or its substitute), must have acquainted it with this pleasure. We would say that the child's lips behaved like an _erogenous zone_, and that the excitement through the warm stream of milk was really the cause of the pleasurable sensation. To be sure, the gratification of the erogenous zone was at first united with the gratification of taking nourishment. He who sees a satiated child sink back from the mother's breast, and fall asleep with reddened cheeks and blissful smile, will have to admit that this picture remains as typical of the expression of sexual gratification in later life. But the desire for repetition of the sexual gratification is separated from the desire for taking nourishment; a separation which becomes unavoidable with the appearance of the teeth when the nourishment is no longer sucked in but chewed. The child does not make use of a strange object for sucking but prefers its own skin because it is more convenient, because it thus makes itself independent of the outer world which it cannot yet control, and because in this way it creates for itself, as it were, a second, even if an inferior, erogenous zone. The inferiority of this second region urges it later to seek the same parts, the lips of another person. ("It is a pity that I cannot kiss myself," might be attributed to it.) Not all children suck their thumbs. It may be assumed that it is found only in children in whom the erogenous significance of the lip-zone is constitutionally reënforced. Children in whom this is retained are habitual kissers as adults and show a tendency to perverse kissing, or as men they have a marked desire for drinking and smoking. But if repression comes into play they experience disgust for eating and evince hysterical vomiting. By virtue of the community of the lip-zone the repression encroaches upon the impulse of nourishment. Many of my female patients showing disturbances in eating, such as hysterical globus, choking sensations, and vomiting, have been energetic thumbsuckers during infancy.