Letters.

        Origen's letters were also numerous and important. A hundred of them were gathered into a collection by Eusebius himself, perhaps in the days when he catalogued the Origen Library at Caesarea for his teacher and patron Pamphilus (Church History vi. 36. 3) Jerome's list of Origen's works, probably taken from that of Eusebius, now lost, mentions others. One of the letters, written to Fabianus, bishop of Rome, in defense of his works, grew to the proportions of a treatise, in two books. But, of all these letters, only two have been preserved: the one to Africanus, in defense of Susanna as part of Daniel, and the one to Gregory Thaumaturgus, who had been converted by him and had been one of his pupils. In it Origen urges his pupils to make full use, in advancing the Christian cause, of all that Greek thought had achieved.

        The enormous quantity of Origen's writing makes it necessary to group it thus according to the various fields with which it dealt. But there is also a value in viewing his principal works in their chronological order. Although Origen's activity as a writer was not notable in the early part of his work at Alexandria, down to 215-16, even in those years he was learning Hebrew and producing his Hexapla. But after his return from Caesarea to the headship of the catechetical school, in z z 7-z 8, when he was about thirty-three, his literary activity began to develop fast. It was in z 18 that he began his lifelong work upon his commentaries, at the suggestion of Ambrose, who provided the publishing facilities already described. In this second Alexandrian period, zip-3o, he produced his four books On First Principles and the ten books of Miscellanies. After his removal to Caesarea in 232 he wrote his exhortation On Martyrdom (235) and his eight books Against Celsus (246-48), the masterpiece of early Christian apologetic.