The following is my own original research into a very strange sidelight of Greek mythology, and it was a gigantic pain to untangle thanks to more than three centuries of scholars copying each other. My thanks go to the great Hellenist M. L. West for his assistance in tracking down the origins of this weird little mistake.
But what bothered me is that I couldn’t find any evidence of Jason ever being called Diomedes in the ancient Greek and Roman literature. Not once.
Here’s where things got complicated.
The scholarly sources all cite the ancient scholia (notes) made on the poet Pindar’s Fourth Pythian Ode, the oldest poem to tell the story of Jason. Specifically, they cite the scholion at verse 211 (old system), commenting on Jason’s claim in the poem that the centaur Chiron, his teacher, called him by the name Jason. At verse 211 the scholiast wrote that Chiron gave Jason his name, but the scholiast does not specify any former name. Neither does the scholiast who repeated the exact same information in the scholia to Apollonius of Rhodes’ Jason epic the Argonautica at 1.554. So where did the name Diomedes come from?
It comes from a scholarly mistake.
In 1567, the Renaissance humanist Natali Conti (Natales Comes) published his monumental Latin-language compilation of Greco-Roman mythology, called Mythologiae, which quickly became the standard mythography of the Renaissance and the basis for nearly all modern mythographies via its use in the Abbé Banier’s influential 1711 mythography.
In the first edition, Conti reported the Pindar/Apollonius scholia correctly: “When Jason had become a man and had learned from Chiron the healing art, he was called Jason” (my translation). But in the expanded edition of 1581, something had changed: “When Jason had become a man and had learned from Chiron the healing art, he was called Jason, having first been called Dolomedes” (my translation).
The Classical scholar Winifred Warren Wilson noted in 1910 that Conti had amended his original line to add information from the Apollonius scholia at 3.26, but he made a mistake. He misread the Greek word δολόμηδες (“crafty”) as a proper name and affixed it to Jason despite the scholion having nothing to do with him.
So far, so good. But how did Dolomedes become Diomedes?
Well, as it turns out, most modern mythographers derive their work, ultimately, from the Abbé Banier, who produced the first scholarly mythography in 1711. According to Winifred Wilson, When Banier developed his mythography, he was using a bad copy of Natali Conti. Banier used the Lyons edition of 1653, based on the Geneva edition of 1651, in which “Diomedes” is misprinted for “Dolomedes.” This typographical error became Banier’s authoritative assertion that Chiron taught Jason “the Sciences, which he himself professed, especially Medicine, and gave him for that Reason the name of Jason, instead of Diomedes, which he had before” (English translation of 1740).
And with the exception of Winifred Wilson and me, for 300 years no one bothered to check the original sources and blindly accepted Banier’s assertion, based on a typographical misprint of Conti’s original error, as accepted fact. If a legitimate scholar said it, it had to be true. Right?