Depth-Psychology.—Psychoanalysis, in its character of depth psychology, considers mental life from three points of view: the dynamic, the economic and the topographical.
From the first of these standpoints, the dynamic one, psycho analysis derives all mental processes (apart from the reception of external stimuli) from the interplay of forces, which assist or in hibit one another, combine with one another, enter into compro mises with one another, etc. All of these forces are originally in the nature of instincts ; that is to say, they have an organic origin. They are characterised by possessing an immense (somatic) per sistence and reserve of power ("repetition-compulsion") ; and they are represented mentally as images or ideas with an affective charge ("cathexis"). In psychoanalysis, no less than in other sciences, the theory of instincts is an obscure subject. An empirical analysis leads to the formation of two groups of instincts: the so-called "ego-instincts," which are directed towards self-preserva tion and the "object-instincts," which are concerned with rela tions to an external object. The social instincts are not regarded as elementary or irreducible. Theoretical speculation leads to the • L. 4, ctinrinmari t ;netinrtc nyl-arb 1;0 cealed behind the manifest ego-instincts and object-instincts: namely (a) Eros, the instinct which strives for ever closer union, and (b) the instinct for destruction, which leads toward the dis solution of what is living. In psychoanalysis the manifestation of the force of Eros is given the name "libido." Pleasure-Pain Principle.—From the economic standpoint psychoanalysis supposes that the mental representations of the instincts have a cathexis of definite quantities of energy, and that it is the purpose of the mental apparatus to hinder any damming up of these energies and to keep as low as possible the total amount of the excitations to which it is subject. The course of mental processes is automatically regulated by the "pleasure-pain principle"; and pain is thus in some way related to an increase of excitation and pleasure to a decrease. In the course of develop
ment the original pleasure principle undergoes a modification with reference to the external world, giving place to the "reality principle," whereby the mental apparatus learns to postpone the pleasure of satisfaction and to tolerate temporarily feelings of pain.
Mental Topography.—Topographically, psychoanalysis re gards the mental apparatus as a composite instrument, and endeavours to determine at what points in it the various mental processes take place. According to the most recent psychoanalytic views, the mental apparatus is composed of an "id," which is the reservoir of the instinctive impulses, of an "ego," which is the most superficial portion of the id and one which is modified by the influence of the external world, and of a "super-ego," which develops out of the id, dominates the ego and represents the inhibitions of instinct characteristic of man. Further, the property of consciousness has a topographical reference ; for processes in the id are entirely unconscious, while consciousness is the function of the eko's outermost layer, which is concerned with the per ception of the external world.
At this point two observations may be in place. It must not be supposed that these very general ideas are presuppositions upon which the work of psychoanalysis depends. On the con trary, they are its latest conclusions and are in every respect open to revision. Psychoanalysis is founded securely upon the obser vation of ttle facts of mental life; and for that very reason its theoretical superstructure is still incomplete and subject to con stant alteration. Secondly, there is no reason for astonishment that psychoanalysis, which was originally no more than an attempt at explaining pathological mental phenomena, should have devel oped into a psychology of mental life. The justification for this arose with the discovery that the dreams and mistakes ("parapraxes," such as slips of the tongue, etc.) of normal men have the same mechanism as neurotic symptoms.