The History of the Decline and Fall of the Roman Empire - Edward Gibbon [297]
[Footnote 108: Aurelius Victor ascribes the abdication, which had been so variously accounted for, to two causes: 1st, Diocletian's contempt of ambition; and 2dly, His apprehension of impending troubles. One of the panegyrists (vi. 9) mentions the age and infirmities of Diocletian as a very natural reason for his retirement.
Note: Constantine (Orat. ad Sanct. c. 401) more than insinuated that derangement of mind, connected with the conflagration of the palace at Nicomedia by lightning, was the cause of his abdication. But Heinichen. in a very sensible note on this passage in Eusebius, while he admits that his long illness might produce a temporary depression of spirits, triumphantly appeals to the philosophical conduct of Diocletian in his retreat, and the influence which he still retained on public affairs. - M.]
The ceremony of his abdication was performed in a spacious plain, about three miles from Nicomedia. The emperor ascended a lofty throne, and in a speech, full of reason and dignity, declared his intention, both to the people and to the soldiers who were assembled on this extraordinary occasion. As soon as he had divested himself of his purple, he withdrew from the gazing multitude; and traversing the city in a covered chariot, proceeded, without delay, to the favorite retirement which he had chosen in his native country of Dalmatia. On the same day, which was the first of May, ^109 Maximian, as it had been previously concerted, made his resignation of the Imperial dignity at Milan.
Even in the splendor of the Roman triumph, Diocletian had meditated his design of abdicating the government. As he wished to secure the obedience of Maximian, he exacted from him either a general assurance that he would submit his actions to the authority of his benefactor, or a particular promise that he would descend from the throne, whenever he should receive the advice and the example. This engagement, though it was confirmed by the solemnity of an oath before the altar of the Capitoline Jupiter, ^110 would have proved a feeble restraint on the fierce temper of Maximian, whose passion was the love of power, and who neither desired present tranquility nor future reputation. But he yielded, however reluctantly, to the ascendant which his wiser colleague had acquired over him, and retired, immediately after his abdication, to a villa in Lucania, where it was almost impossible that such an impatient spirit could find any lasting tranquility.
[Footnote 109: The difficulties as well as mistakes attending the dates both of the year and of the day of Diocletian's abdication are perfectly cleared up by Tillemont, Hist. des Empereurs, tom. iv. p 525, note 19, and by Pagi ad annum.]
[Footnote 110: See Panegyr. Veter. vi. 9. The oration was pronounced after Maximian had resumed the purple.]
Diocletian,