Since the Middle Ages, the Catholic Church has recognized individuals known for their theological learning and spiritual wisdom with the formal title “Doctor of the Church.” At first the title applied only to four of the Latin Fathers of the Church, Jerome, Ambrose, Augustine, and Gregory the Great. Before long, to balance things off, four Greek Fathers were named: Athanasius, Basil, Gregory of Nazianzus, and Gregory of Nyssa. But since the mid-sixteenth century, another two dozen have had the title officially conferred upon them. These include, for example, Church Fathers (Venerable Bede, Cyril of Alexandria, John of Damascus, and Ephrem of Syria); medieval theologians (Anselm of Canterbury, Albert the Great, Thomas Aquinas, and Bonaventure); and mystics (John of the Cross, Francis de Sales, and the only two female Doctors, Catherine of Siena and Teresa of Avila).