A Hermetic symbol of the sexual power, mentioned by Hermes Trismegistus in his twelfth book.
Hermes: Reason (Logos) indeed, O Tat, among all men hath He distributed, but Mind not yet; not that He grudgeth any, for grudging cometh not from Him, but hath its place below, within the souls of men who have no Mind.
Tat: Why then did God, O father, not on all bestow a share of Mind?
Hermes: He willed, my son, to have it set up in the midst for souls, just as it were a prize.
Tat: And where hath He set it up?
Hermes: He filled a mighty Cup with it, and sent it down, joining a Herald [to it], to whom He gave command to make this proclamation to the hearts of men: Baptize thyself with this Cup's baptism, what heart can do so, thou that hast faith thou canst ascend to him that hath sent down the Cup, thou that dost know for what thoudidst come into being! —The Twelfth Book of Hermes Trismegistus