Symeon the New Theologian
Our venerable and God-bearing father Symeon the New Theologian (949–1022) is one of three saints of the Orthodox church to have been given the title of Theologian (the others are St. John the Apostle and St. Gregory Nazianzen). Born in Galatia and educated at Constantinople, he became abbot of the monastery of St. Mamas. His feast day is celebrated by some on March 12, the date of his repose, while others commemorate his feast on October 12, because March 12 falls within Great Lent.
Some of his writings are included in the Philokalia.