Damascene, John
Damascene's eighth-century treatise on the elements of the faith provides an admirable summary of the Christianity which was expounded by the Greek Fathers of the preceding centuries. His work was much admired and studied by the medieval Latin theologians�indeed, he is often quoted by Aquinas, in the Summa Theologica�and his hymns are still sung in the Greek liturgy.
Born in A.D. 675 in Damascus, the son of a Christian official in the court of Abdul Malik, caliph of that Muslim city, John was educated in the Christian faith by a Calabrian monk who was held a prisoner at Damascus. John succeeded to his father's civic office and for some years continued in it, before transferring his energies to theology and monasticism. In his mid twenties, he joined the already venerable monastery of Mar Sabas, in the Judean wilderness between Bethlehem and the Dead Sea, and lived there until his death.
Among other things, he is noted for his opposition to the iconoclastic movement. When the emperor Leo 3 lent his support to iconoclasm and ordered that all sacred images be destroyed, John Damascene was able to voice a strong protest, largely because he lived in a territory under Muslim rule, and under the protection of the Caliph. He was also a strong proponent of the doctrine of the Virgin Mary's bodily assumption into heaven.
To John of Damascus, therefore, belongs the merit of being the first to compose a volume packed with the sentences of Catholic teachers. Accordingly his authority among theologians was always weighty, not only in the East but even in the West among the Latins; all the more so after the translation into Latin of his book "Concerning the Orthodox Faith," by Burgundio, a citizen of Pisa, during the Pontificate of Eugenius 3. Further if was this translation that was used by that master of systematic doctrine, Thomas Aquinas, and other later theologians.
The customary division among the Latins of the work "Concerning the Orthodox Faith" into four books is found in no Greek codex, nor in the Greek edition of Verona. And, further, that division is not met with in the old manuscripts of the original Latin translation, except as a chance note written in ink by a second and later hand on the margins of some of them. Traces of it however, exist in the books of Aquinas it may well be that this mode of division was devised and introduced by the Latins in imitation of the four books of "Sentences" of Peter Lombard.