Xenophon Hellenica 5.4.2

[2]
  There was a certain Phillidas, who acted as secretary to Archias and his fellow polemarchs ¹ and in other ways served them, as it seemed, most excellently. Now this man went to Athens on a matter of business, and there met Melon, one of the Thebans in exile at Athens and a man who had been an acquaintance of his even before this time. Melon, after learning of the doings of the polemarch Archias and the tyrannous rule of Philippus, and finding out that Phillidas hated the conditions that existed at home even more than he himself did, exchanged pledges with him and came to an agreement as to how everything should be managed.