“The Left Hand of Darkness” is a novel published by Ursula K. Le Guin in 1969, featuring an anthropomorphic specie on another planet, where individuals do not have a fixed gender, instead undergoing periodic spontaneous change into male or female, while being asexual most of the time. And they can control this process by using hormones. I wonder how this piece of science fiction correlates with the actual history: Magnus Hirschfeld in 1918 at his Institute for Sexual Science in Berlin was one of the first to offer his patients the means to achieve sex change, either through hormone therapy, sex change operations, or both.