Dionysius Exiguus

Dionysius was born around 470 in Scythia Minor, part of a community of Eastern Roman monks centered in Tomis on the Black Sea. By 500 he'd moved to Rome, where he spent the rest of his life as a monk — not an abbot, despite later honorifics, but a senior and respected member of his community. He translated 401 Church canons from Greek into Latin, codifying the decrees of major councils from Nicaea to Chalcedon; these collections carried such weight they still guide church administration today. He also wrote on elementary mathematics and devised the computus that nearly every church adopted for…