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James Mills Peirce: “Professor X”

Mathematical Tables

Title page of Mathematical Tables Chiefly to Four Figures by James Mills Peirce, 1896

Homosexual case studies populated late-century medical literature. In Krafft-Ebing's book Psychopathia Sexualis (1893), “Case 99,” a male, “never lost for an instant the feeling of being a woman.”[1] Case 106, identified as “Mrs. M,” “would run after pretty girls . . . for hours at a time.”[2]

The book, Sexual Inversion, by influential British sexologist Havelock Ellis also contained in-depth case histories. In 1897 it featured a letter by “Professor X.” Circumstantial, but very convincing evidence has identified the letter writer as Harvard math professor, James Mills Peirce.[3] He wrote, “[W]e ought to think and speak of homosexual love, not as 'inverted' or 'abnormal' . . . but as being in itself a natural, pure and sound passion.”[4]


1. R. von Krafft-Ebing, Psychopathia Sexualis, with Especial Reference to Contrary Sexual Instinct: A Medico-Legal Study, authorized translation…by Charles Gilbert Chaddock (Philadelphia: F.A. Davis, 1893), 211.

2. Krafft-Ebing, 233.

3. Hubert Kennedy, “The Case for James Mills Peirce” in his “Six Articles on James Mills Peirce” (Concord: Peremptory, 2003), 13, http://hubertkennedy.angelfire.com/Peirce.pdf.

4. Jonathan Katz, Gay American History: Lesbians and Gay Men in the U.S.A. (New York: Thomas Y. Crowell, 1976), 376.