21 Jupiter is troubled enough, being overwhelmed with fear, and cannot find means to soothe the rage of his violated mother. He pours forth prayers, and makes supplication; her ears are closed by grief. The whole order of the gods is sent to seek his pardon; no one has weight enough to win a hearing. At last, the son seeking how to make satisfaction, devises this means: Arietem nobilem bene grandibus cum testiculis deligit, exsecat hos ipse et lanato exuit ex folliculi tegmine.
Approaching his mother sadly and with downcast looks, and as if by his own decision he had condemned himself, he casts and throws these into her bosom. When she saw what his pledge was, she is somewhat softened, and allows herself to be recalled to the care of the offspring which she had conceived. After the tenth month she bears a daughter, of beautiful form, whom later ages have called now Libera, now Proserpine; whom when Jupiter Verveceus saw to be strong, plump, and blooming, forgetting what evils and what wickedness, and how great recklessness, he had a little before fallen into, he returns to his former practices; and because it seemed too wicked that a father openly be joined as in marriage with his daughter, he passes into the terrible form of a dragon: he winds his huge coils round the terrified maiden, and under a fierce appearance sports and caresses her in softest embraces.
She, too, is in consequence filled with the seed of the most powerful Jupiter, but not as her mother was, for she bore a daughter like herself; but from the maiden was born something like a bull, to testify to her seduction by Jupiter. If any one asks who narrates this, then we shall quote the well-known senarian verse of a Tarentine poet which antiquity sings, saying: “The bull begot a dragon, and the dragon a bull.” Lastly, the sacred rites themselves, and the ceremony of initiation even, named Sebadia, might attest the truth; for in them a golden snake is let down into the bosom of the initiated, and taken away again from the lower parts.
Source: Against the Heathen (New Advent)