Pantagruel asked him whether he could also make old men young again.

He said he could not.

But the way to make them new men was to get 'em to cohabit with a new-cast female; for this they caught that fifth kind of crinckams, which some call pellade, in Greek, ophiasis, that makes them cast off their old hair and skin, just as the serpents do, and thus their youth is renewed like the Arabian phoenix's.

This is the true fountain of youth, for there the old and decrepit become young, active, and lusty.
Just so, as Euripides tells us, Iolaus was transmogrified; and thus Phaon, for whom kind-hearted Sappho run wild, grew young again, for Venus's use; so Tithon by Aurora's means; so Aeson by Medea, and Jason also, who, if you'll believe Pherecides and Simonides, was new-vamped and dyed by that witch; and so were the nurses of jolly Bacchus, and their husbands, as Aeschylus relates..