The expulsion of foreigners from Alexandria causes Ambrose to take refuge in Caesarea, where he seems to have made his permanent home; and Origen leaves Egypt, apparently going with Ambrose to Caesarea, where he spends some time.

Here, in conformity with local usage based on Jewish custom, Origen, though not ordained, preaches and interprets the Scriptures at the request of the bishops Alexander of Jerusalem and Theoctistus of Caesarea.

When, however, the confusion in Alexandria subsides, Demetrius, bishop of Alexandria, who views this activity as a breach of discipline, orders him, probably in about 216, to return to Alexandria.

Little is known of Origen's activity during the next decade, but it is probably devoted to teaching and writing.

The latter is rendered the more easy for him by Ambrose, who provides him with more than seven stenographers to take dictation in relays, as many scribes to prepare longhand copies, and a number of girls to multiply the copies.

At the request of Ambrose, he now begins a huge commentary on the Bible, beginning with John, and continuing with Genesis, Psalms 1-25, and Lamentations, besides brief exegeses of selected texts (forming the ten books of his Stromateis), two books on the resurrection, and the work On First Principles.