The first book of Macrobius' Saturnalia, written probably in the 430s AD, includes a historical exposition of the Roman calendar with a dramatic date some fifty years earlier, set in the mouth of the learned senator Vettius Agorius Praetextatus, followed by more technical detail at the request of an Egyptian named Horus, who as a foreigner is allowed to seek elementary information for which no one brought up in Roman culture would need to ask. This...