City of God

In support of this story, Varro relates others no less incredible about that most famous sorceress Circe, who changed the companions of Ulysses into beasts, and about the Arcadians, who, by lot, swam across a certain pool, and were turned into wolves there, and lived in the deserts of that region with wild beasts like themselves. But if they never fed on human flesh for nine years, they were restored to the human form on swimming back again through the same pool. Finally, he expressly names one Demænetus, who, on tasting a boy offered up in sacrifice by the Arcadians to their god Lycæus according to their custom, was changed into a wolf, and, being restored to his proper form in the tenth year, trained himself as a pugilist, and was victorious at the Olympic games. And the same historian thinks that the epithet Lycæus was applied in Arcadia to Pan and Jupiter for no other reason than this metamorphosis of men into wolves, because it was thought it could not be wrought except by a divine power. For a wolf is called in Greek λυκὸς, from which the name Lycæus appears to be formed. He says also that the Roman Luperci were as it were sprung of the seed of these mysteries.