Gregory of Nyssa
Bishop of Nyssa in Cappadocia, mystical theologian and one of the three 'Cappadocian Fathers' (c. 335–c. 395), younger brother of Basil of Caesarea and close friend of Gregory of Nazianzus, initially trained as a professional rhetorician before devoting himself fully to ecclesiastical life, generally regarded as the most speculative and philosophically sophisticated of the three Cappadocian fathers and one of the founders of Christian mystical theology proper. Consecrated bishop under pressure from his own brother Basil, Gregory played a decisive role in the definitive consolidation of Nicene Trinitarian doctrine at the First Council of Constantinople (381), following Basil's premature death, systematically and philosophically defending the distinction between the single substance (ousia) and the three persons or hypostases (Father, Son, Holy Spirit) of the Trinity. His most original and influential theological contribution is the doctrine of 'epectasis' (epektasis), developed above all in The Life of Moses and the Homilies on the Song of Songs, according to which, since God is infinite and inexhaustible, the human soul, both in this life and in the eternity to come, never arrives at a final, static state of spiritual perfection but progresses in a perpetual, ever-growing movement toward a God who always reveals himself beyond what has already been attained — a dynamic conception of holiness and eternal life radically different from the more common static notions of contemplative repose within the tradition. Gregory also developed a universalist doctrine of final salvation — 'apocatastasis', the eventual restoration of all creation, including demons, to communion with God — a controversial position that sets him apart from most later patristic theologians and remains a subject of theological debate. His profound influence on the development of apophatic Christian mysticism, which stresses the ultimate unknowability of God beyond all human concepts, would be decisively felt in later thinkers such as Pseudo-Dionysius the Areopagite.