Heinrich Kaan's "Psychopathia Sexualis" (1844)"With Heinrich Kaan's book we have then what could be called the date of birth, or in any case the date of the emergence, of sexuality and sexual aberrations in the psychiatric field." Michel Foucault, Abnormal: Lectures at the Collge de France, 19741975. Heinrich Kaan's fascinating workpart medical treatise, part sexual taxonomy, part activist statement, and part anti onanist tracttakes us back to the origins of sexology. He links the sexual instinct