The Cappadocian Fathers (or Cappadocian philosophers) are Basil the Great (330-379), who was bishop of Caesarea; Basil's brother Gregory of Nyssa (c.330-395), who was bishop of Nyssa; and a close friend, Gregory Nazianzus (329-389), who became Patriarch of Constantinople . The Cappadocia Region, in modern-day Turkey, was early a site of Christian activity, with several missions by Paul in this region. The Cappadocian Fathers advanced the development of early Christian theology, for example the doctrine of the Trinity, and are highly respected as saints in both Western and Eastern churches.