Mosshammer Alden A. The Easter Computus and the Origin of the Christian Era

Oxford: Oxford University Press, 2008. — 474 p.The arrival of the third millennium in the western calendar and the debate over whether the year 2000 or 2001 should mark its beginning occasioned a plethora of newspaper columns and internet conversation dedicated to the topic. Thanks to all of this interest in the new millennium, one of the few relatively well-known facts from late antique Roman history is that it was Dionysius Exiguus who introduced our now ‘common era’ reckoned from the birth of Jesus — anno domini nostri Jesu Christi, the year of the Lord Jesus Christ. A notice on the website of the Royal Observatory represents the prevailing wisdom.Early in the 6th century ad, Dionysius Exiguus (Denys the Little), a monk and astronomer from Scythia (now SW Russia), compiled a table of dates for Easter in terms of the Diocletian calendar. He decided to reset the system of counting years to honour the birth of Christ so that the year 248 Anno Diocletiani became the year 532 Anno DominiNostri Jesu Christi, known as 532 ad for short. In his scheme he believed that Christ was born on the 25th of December of the year preceding the start of the year 1 ad. There is no year 0 ad preceding the year 1 ad. Indeed, the concept of counting from zero, rather than one, does not exist in Latin and was introduced into Europe from the Middle East many centuries later. Therefore, Dionysius’ calendar places the birth of Jesus Christ at the end of the year 1 bc. However, modern research indicates that Christ was probably born in 6 bc and certainly by 4 bc, when Herod died.