*Diverse Sexual Constitutions.*--(_a_) We have considered above the possibility of establishing the manifold character of congenital sexual constitutions through the diverse formation of the erogenous zones; we may now attempt to do the same in dealing with the indirect sources of sexual excitement. We may assume that, although these different sources furnish contributions in all individuals, they are not all equally strong in all persons; and that a further contribution to the differentiation of the diverse sexual constitution will be found in the preferred developments of the individual sources of sexual excitement. *The Paths of Opposite Influences.*--(_b_) Since we are now dropping the figurative manner of expression hitherto employed, by which we spoke of _sources_ of sexual excitement, we may now assume that all the connecting ways leading from other functions to sexuality must also be passable in the reverse direction. For example, if the lip zone, the common possession of both functions, is responsible for the fact that the sexual gratification originates during the taking of nourishment, the same factor offers also an explanation for the disturbances in the taking of nourishment if the erogenous functions of the common zone are disturbed. As soon as we know that concentration of attention may produce sexual excitement, it is quite natural to assume that acting on the same path, but in a contrary direction, the state of sexual excitement will be able to influence the availability of the voluntary attention. A good part of the symptomatology of the neuroses which I trace to disturbance of sexual processes manifests itself in disturbances of the other non-sexual bodily functions, and this hitherto incomprehensible action becomes less mysterious if it only represents the counterpart of the influences controlling the production of the sexual excitement. However the same paths through which sexual disturbances encroach upon the other functions of the body must in health be supposed to serve another important function. It must be through these paths that the attraction of the sexual motive-powers to other than sexual aims, the sublimation of sexuality, is accomplished. We must conclude with the admission that very little is definitely known concerning the paths beyond the fact that they exist, and that they are probably passable in both directions. [1] For it is really impossible to have a correct knowledge of the part belonging to heredity without first understanding the part belonging to the infantile.