Gregory of Nyssa, the Christian theologian and Father of the Eastern church, was born in Cappadocia. Resisting the invitation of his brother, Basil the Great, to join his monastic community at Annesis, Gregory married and became a teacher of rhetoric. In 372 Basil, bishop of Caesarea, had Gregory appointed bishop of Nyssa; but Gregory was deposed in 374 by a local synod dominated by the Emperor Valens and the Arian party. Restored to his see in 377, Gregory began to grow closer to Basil's monastic and theological ideals. After Basil's death in 379, Gregory engaged more and more in writing and in the vigorous administration of his diocese; he was an important figure at the councils convoked at Constantinople in 381, 383, and, just before his death, in 394. An ardent defender of the orthodox Trinitarian doctrine of Nicaea against the Arians and semi-Arians, he...