Gregory of Nazianzus, a 4th-century bishop of Constantinople, receives relatively little attention from modern Western scholars, yet he is one of the most influential theologians in the history of Christian doctrine. As an advocate for the conceptual understanding of the Trinity, Gregory set precedents for the way his fellow and future Christians would perceive and worship God. Christopher A. Beeley presents the first comprehensive study in modern Western scholarship of Gregory's doctrine of the Trinity in the full range of his theological and practical vision of the Christian life.