Synopsis of The Greek Alexander Romance
The Alexander Romances, which grew out of Pseudo-Callisthenes’ fanciful history, have Nectanabo, the last king of Egypt and a sage, fleeing Egypt when he sees that the gods have deserted Egypt. He has a vision that he will return as a young man who will circle the world.
He ends up in Pella where he practises as a soothsayer and astrologer. His fame is such that Olympias consults him when Philip is away as she has heard rumours that Philip will desert her and marry another. Nectanabo reads her horoscope and says that this will eventually come true but not before she has met “an earth-born god, and be embraced by him and conceive a son, your own child, an avenger of the sins of Philip”. She asks who the god is “The god of Libya, the horned, wealth-bringing Ammon.”
Nectanabo works his magic and Olympias dreams of Ammon “embracing her and, after he arose, saying: "Madam, in your womb you carry your avenger."*. Olympias, convinced by the dream, agrees to it in reality and Nectanabo tells her “For this god on his coming to you will become first a serpent creeping over the earth with a hissing sound, then he will be transformed into the horned Ammon, then into mighty Heracles, then into Dionysus bearing the thyrsus. Finally, arriving a god in human form, he will appear in the semblance of myself." He collects a ram’s fleece, horns, white robe, a staff, and makes a snake which he releases into Olympias’s room. This happens as predicted, the snake transforms into a god “And he put aside the date-tree wood staff, got up onto the bed and turned Olympias toward him and mated with her. And he, when he arose from her, smote her belly and said: "O child, remain forever unconquered, supreme!"
Nectanabo, disguised as a god, slept with Olympias as many times as she desired and she began to worry about Philip’s reaction to her pregnancy. Nectanabo bewitched a sea falcon and made it the bearer of a dream to Philip who saw “a god, handsome, hoary, horned, the image of Ammon” lying with Olympias. He saw “the man drew her image on a papyrus from the Nile and sealed it with a golden seal having on the stone a symbol with the head of a lion, the might and darting brightness of the sun.” Philip called for an interpreter of dreams who assured him that Olympias had been impregnated by a god, and Philip was reconciled with her. When Philip showed signs of suspicion, Nectanabo changed himself into a large serpent who kissed Olympias before Philip and his courtiers.
When the time was approaching for Olympias to give birth, Philip saw an omen which was interpreted to mean that the son born would encircle the world but would not return home to die. When Olympias went into labour, she sat on the birthing seat but Nectanabo told her to get up and walk about as now was not an auspicious astrological moment for the child to be born. “So he who is born under such conditions dies, smitten by fire.“. “Await now this star of Hermes, Queen, beside the One of Ill Name of the goat horns. So you will bear a famous warrior of a different mind, your own son.”
“And he himself delivered her child and said, "If you give birth now, O Queen, the one you bear is a world conqueror." And Olympias cried out louder than a bull and gave birth to a boy child. At this word, the infant fell on the ground. Lightning flashed, thunder rumbled, earth shook, so that all the universe was in commotion.”
http://www.attalus.org/translate/alexander1a.html
* Used by Oliver Stone in Alexander (2004)