Aurelius Ambrosius was a fourth century cleric who rose to become the Archbishop of Milan in 374 AD. On the Duties of the Clergy was published in about 391 AD. It was written to motivate the clergy of his diocese so that they would conduct their lives in a manner appropriate to their vocation. With his immense background in the Classics, Ambrose modeled his treatise on Cicero's De Officiis.