In his later life, fourth- and fifth-century historian Philostorgius wrote a twelve-volume history of the church, covering the period from the beginning of the Arian schism to the year 425 AD. The massive work no longer exists in its entirety, but this volume contains what remains: “an epitome of [his ecclesiastical history] compiled by Photius, who was appointed to the Patriarchal see of Constantinople, AD 853, and under whom the schism between Eastern and Western churches was formally consummated.” Photius I, or St. Photius the Great, a ninth-century historian, is regarded by many as the most influential Patriarch of Constantinople since John Chrysostom, as well as an eminent intellectual of his time. In The Ecclesiastical History of Philostorgius, he carefully sifts through Philostorgius’ detailed church history and provides the essence of each of the original volumes. Translated into English for the first time by Edward Walford, this work offers a compelling look at the Arian Controversy, supplemented by Walford’s many helpful footnotes.