Today is the Feast of St. John of Damascus. John was a Syrian Christian; his name at birth may have been Mansur ibn Sarjun al-Taghlibi -- our records are not wholly clear, and if I understand correctly it is possible that this was really the name of his father. The family of Mansur was a family of fair local importance in a time of great change: John's grandfather was in charge of taxes under the Byzantine Empire, and then, when the region was conquered by the Umayyad caliphate, the family continued in the civil service, working for the caliph (which was common among the civil servants of the time). Indeed, John's father, Sarjun, was put in charge of building the Arab fleet for the purpose of attacking Constantinople. John himself served in the court of the caliph for some time, before going to the Mar Saba monastery. It was there, at Mar Saba, that he took the name John as his monastic name. He wrote quite a few important works, the most important of which is the one usually known in the west as the Exposition of the Orthodox Faith. Because he's primarily a synthesizer of doctrine, his creativity is often overlooked; as with most synthesizing geniuses, the creative ingenuity he constantly displays is not flashy and obvious but often very subtle. He is sometimes called Chrysorrhoas, which means, "streaming with gold."
Tolstoy's cousin, Count Alexei Tolstoy, wrote a poem about John of Damascus that became the core of a famous cantata by Taneyev, Ioann Damaskin, also sometimes called A Russian Requiem. It is Russian music at its finest, and streaming with gold itself. The following is but an excerpt (the third movement).