Clinical psycho-analytic practice has proved that no matter what the given clinical entity of mental disturbance, every psychopathological state has its intimate individual history. We have not yet at our disposal any definite criteria by means of which we can measure and subtract the degree of identification from direct hereditary influence. This vitiates in advance the results of any study of heredity. Only if it were possible clinically to follow through the developmental vicissitudes of the various instinctual drives, which in a variety of constellations make up the individual members of a family, could we gain insight into which elements represent heredity