What are emotions? This is the first question the reader will expect to have answered. It is important for our problem to clarify what emotions are; it is difficult to see how, without such a clarification, the search for the relation of memory and emotion can become meaningful. Although we attempted to show in Chapter I that the concept and theory of both memory and emotions are in a process of reformation, there seems to be a difference between the status of the two. The concept "memory" will be more generally taken for granted than that of "emotions": "memory" is used at present in an all too narrow sense, a sense which prevents the mutual elucidation and unitary organization of such fields as perception memory, dream, phantasy, and thinking, but which at least makes for clarity of meaning. The concept "emotion," however, is used so broadly that it is difficult to ascertain its precise meaning. It will be our aim to clarify this meaning. First, we shall enumerate and discuss a few recent attempts at defining emotions; secondly, we shall survey the literature of the physiology of emotions; thirdly, we shall summarize the literature of the psychology of emotions; fourthly, we shall discuss the implications of a number of recent investigations which deal with the role of emotions in other processes of the human organism, such as learning, education, and bodily changes.Before commencing the course of discussion as outlined, a short appraisal of the complexity of the problem will be appropriate. What do we imply if we designate as "emotional disturbances" such a variety of phenomena as psychoses, neuroses, certain somatic maladies-hypertension, gastric ulcer -and behavior and educational difficulties? Is the implication of the term here identical with its implication in the phrase "emotional influence on memory"? Why is it that we speak without hesitation of the "emotional" character and origin of these problems, but investigations and discussions rarely make clear the sense in which they are "emotional"? Why is it that the systematic treatment of the problem of emotions deals in the main with the expressive movements, physiology, and localization of nervous action in emotions? It is not within our present scope to advance an * See also "Feelings and Emotions; The Wittenberg Symposium" (7), and Waahbum,M. ( 8).