But inversion of the sexual instinct is a vastly different thing from perversity in the sexual act. The first, as I have said, is a psycho-pathological condition; while the other, however clearly concrete, may be but a mere phenomenon of accident. One is an anomaly of organic central constitution, of neuropathic predisposition, a manifestation of sexual degeneration not due to any external cause; while the other may be the exact reverse of all three. In the former case, it has the force of a congenital phenomenon, innate sexual inversion; while in the latter, the form in which I am about to consider it, a normal sexual beginning is inferred, to which has been added, by various definite external influences, a secondary character which brings it within the realm of acquired homosexuality.

Of course there are various degrees of the abnormality, ranging all the way from simple hermaphrodism, through the partial homosexuality, which affects only the physical life, to those typical cases in which both the physical and psychical elements are involved; but, since any more minute subdivision would make the subject far too complicated for present purposes, I have deemed it prudent to follow, in the main, the established elussificaf ion.