Diocletian and the Druidess
Vopiscus
14. I do not consider it too painstaking or yet too much in the ordinary manner to insert a story about Diocletian Augustus that seems not out of place here — an incident which he regarded as an omen of his future rule. This story my grandfather related to me, having heard it from Diocletian himself. "When Diocletian," he said, "while still serving in a minor post, was stopping at a certain tavern in the land of the Tungri in Gaul, and was making up his daily reckoning with a woman, who was a Druidess, she said to him, 'Diocletian, you are far too greedy and far too stingy,' to which Diocletian replied, it is said, not in earnest, but only in jest, 'I shall be generous enough when I become emperor.' At this the Druidess said, so he related, 'Do not jest, Diocletian, for you will become emperor when you have slain a Boar (Aper).'"
15. Now Diocletian always had in his mind a desire to rule, as Maximian knew and my grandfather also, to whom he himself told these words of the Druidess. Then, however, reticent, as was his wont, he laughed and said nothing. Nevertheless, in hunting, whenever there was opportunity, he always killed the boars with his very own hand. In fact, when Aurelian received the imperial power, then Probus, then Tacitus, and then Carus himself, Diocletian remarked, "I am always killing boars, but the other man enjoys the meat." It is now well known and a common story that when he had killed Aper, the prefect of the guard, he declared, it is said, "At last I have killed my fated Boar." .My grandfather also used to say that Diocletian himself declared that he had no other reason for killing him with his own hand than to fulfill the Druidess' prophecy and to ensure his own rule. section 6For he would not have wished to become known for such cruelty, especially in the first few days of his power, if Fate had not impelled him to this brutal act of murder.
Vopiscus. "The Lives of Carus, Carinus and Numerian." Historia Augusta. translation by David Magie. Loeb Classical Library, 1932.