The real distinction would seem, therefore, to be between a homosexual impulse so strong that it subsists even in the presence of the heterosexual object, and a homosexual impulse so weak that it is eclipsed by the presence of the heterosexual object.  We could not, however, properly speak of the latter as any more “spurious” or “pseudo” than the former.  A heterosexual person who experiences a homosexual impulse in the absence of any homosexual disposition is not today easy to accept.  We can certainly accept the possibility of a mechanical or other non-sexual stimulus leading to a sexual act contrary to the individual’s disposition.  But usually it is somewhat difficult to prove, and when proved it has little psychological significance or importance.  We may expect, therefore, to find “pseudo-homosexuality,” or spurious homosexuality, playing a dwindling part in classification.

The simplest of all possible classifications, and that which I adopted in the earlier editions of the present Study, merely seeks to distinguish between those who, not being exclusively attracted to the opposite sex, are exclusively attracted to the same sex, and those who are attracted to both sexes.  The first are the homosexual, whether or not the attraction springs from genuine inversion.  The second are the bisexual, or, as they were formerly more often termed, following Krafft-Ebing, psycho-sexual hermaphrodites.[135] There would thus seem to be a broad and simple grouping of all sexually functioning persons into three comprehensive divisions:  the heterosexual, the bisexual, and the homosexual.

Even this elementary classification seems however of no great practical use.  The bisexual group is found to introduce uncertainty and doubt.  Not only a large proportion of persons who may fairly be considered normally heterosexual have at some time in their lives experienced a feeling which may be termed sexual toward individuals of their own sex, but a very large proportion of persons who are definitely and markedly homosexual are found to have experienced sexual attraction toward, and have had relationships with, persons of the opposite sex.  The social pressure, urging all persons into the normal sexual channel, suffices to develop such slight germs of heterosexuality as homosexual persons may possess, and so to render them bisexual.  In the majority of adult bisexual persons it would seem that the homosexual tendency is stronger and more organic than the heterosexual tendency.  Bisexuality would thus in a large number of cases be comparable to ambidexterity, which Biervliet has found to occur most usually in people who are organically left-handed.[136] While therefore the division into heterosexual, bisexual, and homosexual is a useful superficial division, it is scarcely a scientific classification.

In the face of these various considerations, and in view of the fact that, while I feel justified in regarding the histories of my cases as reliable so far as they go, I have not been always able to explore them extensively, it has seemed best to me to attempt no classification at all.