Caduceus, fateful rod, and Orcus

Meaning

II.4.31 interprets Mercury's wings, hat and fateful rod through the world-spirit's passage between higher and lower regions and its power over life and death. The caduceus is an emblem of that movement and efficacy, not a prescription for constructing a magical instrument. The Virgilian reference to Orcus supplies the underworld pole of the comparison. The rod is entwined with serpents, explicitly signifying renewing power, and represents powerful Nature. It opens heaven and earth and gives death and life; descent to the underworld is glossed here as descent into earth. In the Virgilian image the same power draws souls from Orcus, induces sleep and closes eyes in eternal slumber.

The genealogy also requires care. In the phrase about the pure and invisible seed of Jupiter, 'which is air' identifies the seed in the supplied English, not Jupiter himself without qualification. Maya is interpreted as earth, so the offspring carries a relation between a receptive earth and an aerial seed. The nearby theriac-and-venom comparison argues that effects depend on relation and use; it is historical medical reasoning, not dosage advice.