Third Sex.

The relative popularity of the term "third sex" is closely connected to its use by some of the most prominent representatives of the early homosexual rights movement in Germany. Both Karl Heinrich Ulrichs and Magnus Hirschfeld used the term "third sex" in their writings and traced its origins back to Plato's Symposium. In this dialogue, Aristophanes propounds a mythological explanation of heteroerotic and homoerotic attraction in connection with the three primordial sexes of mankind: male-male, male-female, and female-female. According to this myth, present-day humans are halves of ancestral composite individuals who belonged to one of these three sexes, whom Zeus punished because of their insolence by dividing them in two.