It is in his treatise Περὶ Ἀρχῶν, or, as it is commonly known under the Latin title, _De Principiis_, that Origen most fully develops his system, and brings out his peculiar principles. None of his works exposed him to so much animadversion in the ancient church as this. On it chiefly was based the charge of heresy which some vehemently pressed against him,—a charge from which even his firmest friends felt it no easy matter absolutely to defend him. The points on which it was held that he had plainly departed from the orthodox faith, were the four following:—_First_, That the souls of men had existed in a previous state, and that their imprisonment in material bodies was a punishment for sins which they had then committed. _Second_, That the human soul of Christ had also previously existed, and been united to the Divine nature before that incarnation of the Son of God which is related in the Gospels. _Third_, That our material bodies shall be transformed into absolutely ethereal ones at the resurrection; and _fourth_, That all men, and even devils, shall be finally restored through the mediation of Christ. His principles of interpreting Scripture are also brought out in this treatise; and while not a little ingenuity is displayed in illustrating and maintaining them, the serious errors into which they might too easily lead will be at once perceived by the reader. It is much to be regretted that the original Greek of the _De Principiis_ has for the most part perished. We possess it chiefly in a Latin translation by Rufinus. And there can be no doubt that he often took great liberties with his author. So much was this felt to be the case, that Jerome undertook a new translation of the work; but only small portions of his version have reached our day. He strongly accuses Rufinus of unfaithfulness as an interpreter, while he also inveighs bitterly against Origen himself, as having departed from the catholic faith, specially in regard to the doctrine of the Trinity. There seems, however, after all, no adequate reason to doubt the substantial orthodoxy of our author, although the bent of his mind and the nature of his studies led him to indulge in many vain and unauthorized speculations. The _Epistle to Africanus_ was drawn forth by a letter which that learned writer had addressed to Origen respecting the story of Susanna appended to the book of Daniel. Africanus had grave doubts as to the canonical authority of the account. Origen replies to his objections, and seeks to uphold the story as both useful in itself, and a genuine portion of the ancient prophetical writings.