Plutarch, Pelopidas
Bernadotte Perrin, Ed.

26. Now, since Alexander the tyrant of Pherae made open war on many of the Thessalians, and was plotting against them all, their cities sent ambassadors to Thebes asking for an armed force and a general. Pelopidas, therefore, seeing that Epaminondas was busy with his work in Peloponnesus, offered and assigned himself to the Thessalians,¹ both because he could not suffer his own skill and ability to lie idle, and because he thought that wherever Epaminondas was there was no need of a second general. [2] Accordingly, after marching into Thessaly with an armed force, he straightway took Larissa, and when Alexander came to him and begged for terms, he tried to make him, instead of a tyrant, one who would govern the Thessalians mildly and according to law. But since the man was incurably brutish and full of savageness, and since there was much denunciation of his licentiousness and greed, Pelopidas became harsh and severe with him, whereupon he ran away with his guards. [3] Then Pelopidas, leaving the Thessalians in great security from the tyrant and in concord with one another, set out himself for Macedonia, where Ptolemy was at war with Alexander the king of the Macedonians. For both parties had invited him to come and be arbiter and judge between them, and ally and helper of the one that appeared to be wronged. [4] After he had come, then, and had settled their differences and brought home the exiles, he received as hostages Philip, the king's brother, and thirty other sons of the most illustrious men, and brought them to live at Thebes, thus showing the Greeks what an advance the Theban state had made in the respect paid to its power and the trust placed in its justice.

This was the Philip who afterwards waged war to enslave the Greeks, but at this time he was a boy and lived in Thebes with Pammenes. Hence he was believed to have become a zealous follower of Epaminondas, perhaps because he comprehended his efficiency in wars and campaigns, which was only a small part of the man's high excellence; but in restraint, justice, magnanimity, and gentleness, wherein Epaminondas was truly great, Philip had no share, either naturally or as a result of imitation.