John Chortasmenos

John Chortasmenos (; – 1436/37) was a Byzantine monk and bishop of Selymbria, who was a distinguished bibliophile, writer, and teacher.

Life Chortasmenos is first attested as a notary of the patriarchal chancery in 1391. He continued to occupy this position until . At some point he became a monk, with the monastic name Ignatios. Eventually he was raised to metropolitan bishop of Selymbria, a post he held by 1431.

Work An ardent bibliophile, Chortasmenos is notable both as a writer as well as a teacher, counting scholars Mark of Ephesus, Bessarion and Gennadius Scholarius among his pupils. . He wrote a hagiography of Constantine the Great and Helena of Constantinople, commentaries on John Chrysostomos and Aristotle, a treatise on hyphenation, as well as poems. Beside the same problem in Diophantus' manuscript next to which Fermat would later write his famous marginalia (Fermat's Last Theorem), Chortasmenos wrote, "Thy soul, Diophantus, be with Satan because of the difficulty of your other theorems and particularly of the present theorem." In 2013, Italian Philologist and historian of Mathematics Fabio Acerbi showed that Chortasmenos wasn't cursing Diophantus because of the same passage next to which Fermat wrote his theorem (II.8), but because of the far more difficult II.7.