His last period was Stoic practise, for so zealously did he practise austerities that his death was, at least, hastened thereby.[446] It is unlikely that he would have followed Stoic precepts without some sympathy for, or acquaintance with their philosophical doctrines; and as we saw above, Porphyry acknowledges Plotinos's writings contain hidden Stoic pieces.[447] Then, Plotinos spent the last period of his life in Rome, where ruled, in philosophical circles, the traditions of Cicero, Seneca, Epictetus, and Marcus Aurelius. That these Stoic practices became fatal to him is significant when we remember that this occurred during the final absence of Porphyry, who may, during his presence, have exerted a friendly restraint on the zealous master. At any rate, it was during Porphyry's regime that the chief works of Plotinos were written, including a bitter diatribe against the Gnostics, who remained the chief protagonists of dualism and belief in positive evil. Prophyry's work, "De Abstinentia," proves clearly enough his Stoic sympathies. Such aggressive enmity is too positive to be accounted for by the mere removal to Rome from Alexandria, and suggests a break of some sort with former friends. Indications of such a break do exist, namely, the permanent departure to his earlier home, Apamea, of his former editor, Amelius. We hear[448] of an incident in which Amelius invited Plotinos to come and take part in the New Moon celebrations[449] of the mysteries. Plotinos, however, refused, on the grounds that "They must come to me, not I go to them." Then we hear[450] of bad blood between this Amelius and Porphyry, a long, bitter controversy, patched up, indeed, but which cannot have failed to leave its mark. Then this Amelius writes a book on the Differences between Plotinos and Numenius, which, in a long letter, he inscribes to Porphyry,[451] as if the latter were the chief one interested in these distinctions. Later, Amelius, who before this seems to have been the chief disciple and editor of Plotinos, departs, never to return, his place being taken by Porphyry. It is not necessary to possess a vivid imagination to read between the lines, especially when Plotinos, in the last work of this period, against the Gnostics, section 10, seems to refer to friends of his who still held to other doctrines.