Otto Weininger's groundbreaking thesis, in which he argues that all people are comprised of masculine and feminine traits, is reproduced here in full.

Considered a classic work of modern Viennese philosophy, Geschlecht und Charakter - in English, Sex and Character - was influential over subsequent works about human psychology and philosophy of the mind. Weininger defines a series of character traits and extremes which he assigns to gender, concluding that no person embodies every trait to the fullest, but is comprised of a mixture of each. He also examines the qualities of motherhood, types and manifestations of genius, and the attributes demonstrated by particular groups. Weininger was born Jewish and had converted to Christianity in 1902; his discussions of Jewishness were later misrepresented by far-right groups.

Weininger's masterwork garnered a surge of attention only months after its publication. Deeply depressed at having been accused of plagiarizing material from other authors, the author rented the old residence of composer Ludwig van Beethoven's for the night, and committed suicide. Renewed appreciation in his book was swift, with intellectuals of the time proclaiming that the work had solved pivotal questions concerning gender and the essence of human nature.