The psychological mechanisms of manic-depressive insanity have been studied exhaustively by Karl Abraham and other psychoanalysts. He looks upon retardation as a symbol of death and interprets it as a defensive reaction, the patient taking refuge in a retarded state to avoid contact with the outer world. The ideas of poverty associated with depressions he considered as symbolic of an inability to love and occurring in individuals who have not obtained sexual gratification in a normal way. When repression is no longer possible mania ensues and the patient enters upon a new existence, all instinctive inhibition being lost. The flight of ideas he looks upon as a reestablishment of infantilism. He suggests these views, however, as tentative. The delusions of the manic-depressive psychoses have been interpreted as an expression of repressed complexes. White[278] would explain these mechanisms as follows:—"Manic-depressive psychosis is the type of extroversion reaction. That is, the patients instead of turning within themselves (introversion) try to escape their difficulties (conflict) by a 'flight into reality.' This flight into reality is the manic phase of the psychosis with its flight of ideas, distractibility and increased psychomotor activity during which the patient seems to be at the mercy almost of his environment having his attention diverted by every passing stimulus. The great activity can be understood as a defense mechanism. The patient appears, by his constant activity to be covering every possible avenue of approach which might by any possibility touch his sore point (complex) and so he rushes wildly from this possible source of danger to that meanwhile keeping up a stream of diverting activities. He is at once running away from his conflict—into reality—and trying to adequately defend every possible approach.... This method I have described as a 'flight into reality' which is the characteristic of the manic phase, while the failure to deal adequately with the difficulty is manifested by the depression of the depressive phase. In the depression the defenses have broken down and the patient is overwhelmed by a sense of his moral turpitude (self-accusatory delusions). This sense of being sinful is the conscious appreciation of tendencies which should have been left behind to become a part of the historical past (the unconscious) in the course of the development of the psyche but which still demand expression.... The benign character of the manic-depressive group of psychoses is explained because of their extroverted mechanism. Reality is the normal direction for the libido and because the direction is normal they more readily result in recovery." The American Psychiatric Association, in its manual designed for the assistance of hospitals for mental diseases in the compilation of statistical data, makes the following suggestions as to the delimitation of the manic-depressive psychoses:—