For All the Saints: John of Damascus

Here's another saint honored on both Eastern and Western (including Protestant) calendars, the Syrian saint named John of Damascus. He was born in 675 or 676 and died on December 4, 749 (or 760, according to this site). He is honored by Catholics as a Doctor of the Church, as a strong defender of the Assumption of the Virgin Mary, and the Eastern Church commemorates his defense of icons. He was a skillful theologian and also a skillful poet, writing hymns that are still used, for instance, in Orthodox Pascha services. Before his service as a monk and priest, he had been a civil servant for the Muslim caliph in Damascus.