The number of the Beast from the Apocalypse of John, commonly known as the "Book of Revelation". One explanation is that 666 is a code name which alludes to the Roman emperor Domitian, who brutally persecuted Christians during his reign. According to this theory, the Christians referred to their oppressor as "Nero reborn". "Nero Caesar" in Greek is "Neron Kaisar". Hoping to keep the full import of the document hidden from the authorities, the author of the Apocalypse translated this title into Hebrew, then added up the numeric value each Hebrew letter represented for a total of six hundred and sixty-six.