January 2 is the joint feast of Sts. Basil the Great (c. 330-379) and Gregory Nazianzen (c. 329-390), the two Cappadocian fathers commemorated together in the Roman calendar since the 9th century. Basil, bishop of Caesarea in Cappadocia, was the great monastic legislator of the East and the defender of the divinity of the Holy Spirit against the Pneumatomachi. Gregory, his friend from the school of Athens, became Patriarch of Constantinople and presided briefly over the First Council of Constantinople (381), which defined the divinity of the Spirit.
The two saints are the Eastern counterparts of Ambrose and Augustine — bishops, doctors, and defenders of the Nicene faith in the late 4th century. Their writings, with those of Gregory of Nyssa (Basil's brother), defined the doctrine of the Trinity that the Church has confessed since. Basil's On the Holy Spirit and Gregory's Theological Orations are the foundational texts of the doctrine.
The two Cappadocian fathers are the natural patrons of the Eastern Catholic churches and of the theologians of the Trinity. Their feast on January 2, kept at Rome since the early Middle Ages, opens the calendar year with the memory of the doctors who taught the Church to confess God as Trinity — Father, Son, and Holy Spirit, one God. The Basilian monastic rule they shaped is still the rule of the Eastern Catholic monks of Italy and the monks of Mount Athos.
