The Riddle of "Man-Manly" Love: The Pioneering Work on Male Homosexuality
The Riddle of "Man-Manly" Love: The Pioneering Work on Male Homosexuality Volumes I & II by Karl Heinrich Ulrichs
Karl Heinrich Ulrichs published some of the earliest known studies on homosexuality, pioneering the theory that homosexuality was congenital, and not a reprehensible disease or behaviour.
"In The Riddle of "Man-Manly" Love, Ulrichs surveys literary, historical, physiological, and other data in his argument that homosexuality is not a disease or a sin, but perfectly natural, and that the strict line of differentiation between men and women has been overemphasized. Turning to the science of embryology, Ulrichs contends that Urnings (his term for homosexuals) result from a crossing of the male and female generative principles during the first crucial stages of fetal development. Thus Urnings are essentially "male" in body, "female" in desire, and different, therefore, from Dionings (i.e., heterosexual men). Homosexuality (and, with that, hermaphroditism and bisexuality) is the work of nature, hence innate and unavoidable."