The calendar of Antiochus and the new birth of the sun
Roger Beck, The Religion of the Mithras Cult in the Roman Empire: Mysteries of the Unconquered Sun, Oxford University Press, 2006, makes the following interesting remark on p.209-10: … the nominal solstice on 25 December, becomes the Sun’s birthday, the ‘Natalis Invicti’, as the Calendar of Filocalus famously notes—to which phrase in Greek (heliou genethlion) […]