From Man to Woman and Back Again: Tiresias, Lactantius Placidus, Narr. 3.5

[Tiresias] qui utramque naturam maris ac feminae fuerat expertus. nam quodam tempore cum serpentes concubitu haerentes baculo percussisset, in mulierem conversus fuerat ac rursus proximo vere eadem usus ratione ac tactu in virum cesserat. 

--Lactantius Placidus, Qui dicitur Narrationes Fabularum Ovidiarum Liber 3 fabula 5

Tiresias had experienced the nature of being a man and a woman. For at some point in his life he had transformed into a woman when he had struck a pair of mating serpents with a stick. He changed back into a man the following spring the same way.

LACTANTIUS PLACIDUS	MAP:
Name:  Lactantius Placidus Date:  5th or 6th century CE Works:  Abridgement of Ovids’ Metamorphoses Commentary on Statius’ Thebaid	REGION  UNKNOWN
BIO:	Timeline:
Little is known about this Christian author, but he is known for his commentary on Statius’ Thebaid and an abridgement of Ovid’s Metamorphoses.	LATE LATIN / BYZANTINE