These include the Στρωματεῖς, a work composed in imitation of the treatise of Clement of the same name, and consisting originally of ten books, of which only three fragments exist in a Latin version by Jerome (Migne, vol. i. pp. 102-107); a treatise on the Resurrection, of which four fragments remain (Migne, vol. i. pp. 91-100); and the treatise Περὶ Ἀρχῶν, _De Principiis_, which contains Origen’s views on the various questions of systematic theology. The work has come down to us in the Latin translation of his admirer Rufinus; but, from a comparison of the few fragments of the original Greek which have been preserved, we see that Rufinus was justly chargeable with altering many of Origen’s expressions, in order to bring his doctrine on certain points more into harmony with the orthodox views of the time. The _De Principiis_ consists of four books, and is translated in the first volume of the works of Origen in this series, to which we refer the reader. PRACTICAL WORKS. Under this head we place the little treatise Περὶ Εὐχῆς, _On Prayer_, written at the instance of his friend Ambrose, and which contains an exposition of the Lord’s Prayer; the Λόγος προτρεπτικὸς εἰς μαρτύριον, _Exhortation to Martyrdom_, composed at the outbreak of the persecution by Maximian, when his friends Ambrose and Protoctetus were imprisoned. Of his numerous letters only two have come down entire, viz. that which was addressed to Julius Africanus, who had questioned the genuineness of the history of Susanna in the apocryphal additions to the book of Daniel, and that to Gregory Thaumaturgus on the use of Greek philosophy in the explanation of Scripture, although, from the brevity of the latter, it is questionable whether it is more than a fragment of the original. (Both of these are translated in the first volume of Origen’s works in this series.) The Φιλοκαλία, _Philocalia_, was a compilation from the writings of Origen, intended to explain the difficult passages of Scripture, and executed by Basil the Great and Gregory of Nazianzus; large extracts of which have been preserved, especially of that part which was taken from the treatise against Celsus. The remains were first printed at Paris in 1618, and again at Cambridge in 1676, in the reprint of Spencer’s edition of the _Contra Celsum_. In the Benedictine edition, and in Migne’s reprint, the various portions are quoted in footnotes under the respective passages of Origen’s writings. EDITIONS OF ORIGEN.