Four Doctors of the Early Christian Church

Borepatch put up a post about the first Christmas Carol, written by Saint Ambrose, one of the Four Doctors of the early Christian Church. I'd never heard of the the Four Doctors, so off to Wikipedia we go. Here we have them in order of their births, and coincidentally, their deaths. The first three (Ambrose, Augustine and Jerome) were contemporaries. This was the same time period that the New Testament of the Bible was being put together. Gregory lived a couple hundred years later. I had definitely heard of Saint Augustine before this, I can't be sure about the rest of them.

Ambrose of Milan - Paolo Veneziano - 14th century

Ambrose of Milan (c. 340 – 397), also known as Saint Ambrose, Bishop of Milan, an influential theologian.

Hl. Hieronymus - Jacques Blanchard - 1632

Jerome (c. 345 – 420), also known as Jerome of Stridon or Saint Jerome, was a Christian priest, confessor, theologian, and historian. He lived in what is now Croatia.

The triumph of Saint Augustine - Claudio Coello - 1664

Augustine of Hippo (354 – 430), also known as Saint Augustine, bishop of Hippo Regius in Numidia, Roman North Africa (roughly northeast Algeria).

Gregory the Great - 12th-century

Pope Gregory I (c. 540 –  604), also known as Saint Gregory the Great, bishop of Rome from 590 to his death.