Iamblichus' Life of Pythagoras

It is worth noting how this report became so prevalent. The Pythian oracle had predicted to Mnesarchus—who had traveled to Delphi for trade with his wife, who was not yet visibly pregnant—that his voyage would be profitable and conform to his wishes. The oracle also stated that his wife was already pregnant and would bring forth a son surpassing in beauty and wisdom all who had ever lived, and who would be of the greatest advantage to the human race in all matters pertaining to the life of man. When Mnesarchus realized that the God had volunteered this information without being asked about a son, and that he would possess an illustrious and truly divine gift, he immediately renamed his wife Pythaïs—after the son and the Delphic prophet—in place of Parthenis, which was her former name. He named the infant, who was soon after born at Sidon in Phoenicia, Pythagoras; signifying by this name that such an offspring had been predicted to him by the Pythian Apollo. We must not, however, credit the assertions of Epimenides, Eudoxus, and Xenocrates, who suspect that Apollo actually had relations with Parthenis and caused her pregnancy, leading to the oracle; this is by no means to be acceptedi.e., It must not be admitted that Apollo was physically connected with Pythaïs; for this would be extremely absurd. The assertions of Epimenides, Eudoxus, and Xenocrates should be viewed as mythological narratives where heroes are said to have Gods as fathers or Goddesses as mothers. The true meaning is as follows: According to ancient theology, between the eternal attendants of divine nature, called "essential heroes"—who are impassive and pure—and the bulk of human souls who descend to earth with passivity and impurity, there must be an order of human souls who descend with impassivity and purity. As there is no vacuum in either incorporeal or corporeal natures, the last link of a superior order must coalesce with the top of the next inferior order..