2. A comprehensive theory of homosexuality must also explain the extreme cases, particularly male homosexuality coupled with complete virility. 3. Sexual parts and genital glands cannot determine homosexuality in those possessing typical normal male genitalia and testicles; neither can the brain itself be the determining factor in genuine homosexuality, because homosexuality cannot be rooted out by the strongest conscious and unconscious heterosexual influences brought to bear upon thought and phantasy,--the condition developing in spite of such influences. 4. Since as a predisposition (not as sexual instinct) homosexuality appears long before puberty and before the actual functioning of the respective genital glands, it suggests that in homosexuals some physiologic action pertaining to “sexuality,” but not necessarily related to the functioning of the genital glands, undergoes some subtle change as the result of which the sexual instinct is turned from its goal. 5. The condition suggests chemical changes, alteration in the chemistry of sexual tension, the latter being fairly independent of the activity of the sexual glands proper, as is shown by the fact that it may be preserved among eunuchs and others who undergo castration. Krafft-Ebing, Hirschfeld and Bloch, as well as many other investigators and writers, have failed to appreciate the psychological factors involved in homosexuality. Every young individual unconsciously patterns its conduct, especially in the matter of its attitudes toward persons of the opposite sex, after some one in the home environment. When the boy, for instance, is raised under conditions which cause him to pattern his actions after the mother-model, to _feel_ himself woman-like, he will unconsciously and automatically imitate feminine ways and adopt woman’s attitudes, in the sexual sphere as well as otherwise. To illustrate this point, if a boy is brought up by a widowed mother, let us say, in a home environment in which there is no male present, the young boy, impelled to imitate some one in order to establish a standard of conduct, copies his mother’s attitude of physical indifference to women and physical interest in men (if she is a normally constituted woman). If the mother, or other feminine guardian, should be homosexually disposed, i.e., showing a physical interest in women and a physical indifference to men, then, by the same token, the boy would tend to develop a sexual interest in women, and become a normal heterosexual man. Every young boy’s ambition, normally, is to be like his father; later, it may be to excel the father--but this identification, under the circumstances, is present. Now, the absence of a father in the house, or the presence of a father of weak character, who suffers in comparison with the mother, tends to force the youth to make his ego-ideal identification with the mother, with results that are not conducive to normality in the sexual life.