The monk Gregory Akindynos (d. 1348) was a chief spokesman in one of the last major dogmatic disputes in the history of Byzantium, the fourteenth-century hesychast controversy. Gregory’s correspondence is an indispensable source for the study of conflicting viewpoints over what constituted the ideal spiritual life, a dispute that had major importance for the subsequent development of Eastern Orthodox theology. In the course of his letters, Gregory moves from an attempt at mediation to one of active opposition to the views of his former teacher and spiritual father Gregory Palamas. The Letters and extensive commentary also provide insights into the cultural and sociopolitical aspects of the time. Angela Constantinides Hero (1926–2014) was Emerita Professor of History at Queens College, City University of New York.