Plutarch
They say that Helios, when he became aware of Rhea’s intercourse with Kronos, invoked a curse upon her that she should not give birth to a child in any month or year; but Hermes, being enamoured of the goddess, consorted with her. Later, playing at draughts with the moon, he won from it the seventieth part of each of the periods of illumination, and from all the winnings he composed five days, and intercalated them as an addition to the three hundred and sixty days. The Egyptians even now call these five days intercalated and celebrate them as the birthdays of the gods. — 12
neosalexandria 