When artists paint on panels and on walls the events of ancient history, they alike delight the eye, and keep bright for many a year the memory of the past. Historians substitute books for panels, bright description for pigments, and thus render the memory of past events both stronger and more permanent, for the painter’s art is ruined by time. For this reason I too shall attempt to record in writing events in ecclesiastical history hitherto omitted, deeming it indeed not right to look on without an effort while oblivion robs noble deeds and useful stories of their due fame. For this cause too I have been frequently urged by friends to undertake this work. But when I compare my own powers with the magnitude of the undertaking, I shrink from attempting it. Trusting, however, in the bounty of the Giver of all good, I enter upon a task beyond my own strength.

The Ecclesiastical History of Theodoret, which begins with the rise of Arianism and closes with the death of Theodore in 429 (despite being completed in 449-450) is very different in style from those of Socrates Scholasticus and Sozomen. It contains many sources otherwise lost, specially letters on the Arian controversy; however, the book is extremely partisan, the heretics being consistently blackened and described as afflicted with the 'Arian plague'. The narrative is more compressed than in the other historians, and Theodoret often strings documents together, with only brief comments between. Original material of Antiochian information appears chiefly in the latter books. Theodoret's sources are in dispute. According to Valesius these were mainly Socrates and Sozomen; Albert Guldenpenning's thorough research placed Rufinus first, and next to him, Eusebius of Caesarea, Athanasius, Sozomen, Sabinus, Philostorgius, Gregory Nazianzen, and, least of all, Socrates. N. Glubokovskij counts Eusebius, Rufinus, Philostorgius, and, perhaps, Sabinus.

The epistles of St. Paul, among which Theodoret reckons the Epistle to the Hebrews, are the only portions of the New Testament on which we possess our author’s commentaries. On them the late Bishop Lightfoot writes, “Theodoret’s commentaries on St. Paul are superior to his other exegetical writings, and have been assigned the palm over all patristic expositions of Scripture. See Schroeckh xviii. p. 398. sqq., Simon, p. 314 sqq. Rosenmueller iv. p. 93 sqq., and the monograph of Richter, de Theodoreto Epist. Paulin, interprete (Lips. 1822.)