“From the time when Dionysius the Sicilian died and his son Dionysius reigned in his stead … 104 years, in the archonship of Nausigenes at Athens （1368 B.C.）”

Parian Chronicle

“His son Dionysius succeeded him and reigned twelve years.”

Diodorus of Sicily Historical Library

“Dionysius: —Son of the Sicilian despot, himself a despot and a philosopher. His writings are Letters and a treatise On the Poems of Epicharmus .”

Suidas Lexicon

“[Dionysius]: When he was driven from power he was asked ‘What good have Plato and philosophy been to you?’and replied ‘They have taught me to bear patiently a reversal of fortune such as this.’”

Plutarch Sayings of Kings

“Dionysius the despot when expelled from Syracuse taught school at Corinth.”

Cicero Tusculan Disputations

“Dionysius the Second once spent some time with Philip son of Amyntas, in the course of which, naturally enough, points arose for discussion, among others this: Philip asked his guest how it was that having inherited so great a position he had been unable to keep it. The answer was apt enough: ‘My father left me all he had with one exception, and that was the luck with which he had won and kept the rest.’ ”

Aelian Historical Miscellanies

“As time wore on, Dionysius, growing both jealous of Dion and fearful of his popularity in Greece, kept back his revenues and entrusted his wealth to his own stewards. Desiring to repair the ill-name he had with the philosophers because of Plato, he now gathered about him many of the reputed wise and learned, and being ambitious of the first place in dialectic, was constrained to make ill use of his misunderstandings of Plato's teaching. Moreover he began to wish for him once more, and to blame himself for making so poor use of him when he had him, nor paying heed to him as he ought. And like the despot he was, always at the mercy of his own caprices and quick to respond to every impulse, it was suddenly all Plato with him, and after using every means in his power he persuaded Archytas the Pythagorean, who had first brought them together, to be his security for his bona fides and summon Plato to his side. Archytas sent off Archedemus to Plato, and Dionysius also dispatched a trireme and some friends of his to beg him to come, and himself wrote in no ambiguous terms to say that it would not go well with Dion if Plato refused to come to Sicily, whereas if he came it would be to his friend's great profit. Many requests too reached Dion from his wife and sister to entreat Plato to comply and to take no excuse. Thus, as Plato says, he came for the third time into the strait of Scylla:

  So to retrace the path of dire Charybdis.
  Odyssey 12. 428

Plutarch Life of Dion

See also Plat. Epp. 1-3, 13, Justin. 21. 5, Ael. V.H. 4. 18, Plut. Dion 9 ff, Diog. L. 3. 21, 23, 2. 61, 66 ff, Luc. Menipp. 13, Paras. 32 f, Ath. 12. 541.

Dionysius named himself a son of Apollo, writing on his tomb:

sprung from a Dorian1 mother's converse with Phoebus

Plutarch The Fortune of Alexander:

To Apollo

For when you addressed the God at Delphi, as those who were then enquiring of the oracle reported, you flattered him by using this very word （ Hail ）, and, as I am told, you have written:

Hail, and preserve in happiness the life of a despot.

Plato Letter to Dionysius

To Asclepius

“[on Democles the flatterer of Dionysius]: … He said that the difference between him and his fellow-ambassadors arose because after supper his colleagues got some of the crew to join them in singing some of the Paeans of Phrynichus and Stesichorus and even of Pindar, whereas he, with the aid of any of the guests who chose, went through the Paeans composed by Dionysius himself. And he undertook to prove his statement. While his accusers, he declared, could remember not even the number of those songs, he himself was ready to sing them all from beginning to end. This calmed Dionysius, and Democles went on: ‘You would do me a favour, Dionysius, if you were to ask one of the professional musicians2 to teach me the Paean you have composed to Asclepius; for this, I understand, is what you have been engaged upon.’”

Timaeus in Athenaeus Doctors at Dinner

1 As Doris of Locri was D.'s mother and Locri a Dorian city, a pun may be intended.

2 or someone who knows it