Plato, Letters 328d

μὲν τὴν Δίωνος ξενίαν τε καὶ ἑταιρίαν ἐν κινδύνοις ὄντως γεγονότος οὐ σμικροῖς. εἴτʼ οὖν πάθοι τι, εἴτʼ ἐκπεσὼν ὑπὸ Διονυσίου καὶ τῶν ἄλλων ἐχθρῶν ἔλθοι παρʼ ἡμᾶς φεύγων καὶ ἀνέροιτο εἰπών· ὦ Πλάτων, ἥκω σοι φυγὰς οὐχ ὁπλιτῶν δεόμενος οὐδὲ ἱππέων ἐνδεὴς γενόμενος τοῦ ἀμύνασθαι τοὺς ἐχθρούς, ἀλλὰ λόγων καὶ πειθοῦς, ᾗ σὲ μάλιστα ἠπιστάμην ἐγὼ δυνάμενον ἀνθρώπους νέους ἐπὶ τὰ ἀγαθὰ καὶ τὰ δίκαια προτρέποντα εἰς φιλίαν τε καὶ ἑταιρίαν ἀλλήλοις

and association with Dion, when he is actually involved in no little danger. Suppose, then, that some evil fate should befall him, or that he should be banished by Dionysius and his other foes and then come to us as an exile and question us in these words—O Plato, I come to you as an exile not to beg for foot-soldiers, nor because I lack horse-soldiers to ward off mine enemies, but to beg for arguments and persuasion, whereby you above all, as I know, are able to convert young men to what is good and just and thereby to bring them always into a state of mutual friendliness