Letter 1625: Since genuine and sincere friendship is guaranteed precisely by the fact that it speaks without fear, it is on this...

On Practicing Virtue Rather Than Merely Praising It. [The Greek manuscript editor's heading; cf. above, Letter 523.] To Diogenes. To you who adorn virtue with your words, but in your deeds act as an advocate for vice, and so resemble those who play-act upon the stage; to you who say what you do not know, and do not confirm by your deeds what you dignify with your words: I advise you not to cease from praising virtue (for that would not be right), but rather to cease from vice, so that on both counts you may be held in good repute.

Virtus non tam prædicanda, quam exercenda. (Vide supr. epist. 523.) Τῷ λόγῳ μὲν τὴν ἀρετὴν κοσμοῦντι, ἔργῳ δὲ τὴν κακίαν πρεσβεύοντι· καὶ δοκοῦτε τοῖς ἐπὶ σκηνῆς παίζουσιν· καὶ λέγοντι μὲν & μὴ γινώσκετε, μηδὲ τοῖς ἔργοις βεβαιοῦντι· & λόγοις σεμνύνει· παραινοῦ τοῦ μὲν ἐπαινεῖν τὴν ἀρετὴν μὴ λήγειν (οὐδὲ γὰρ δὲ- καιον), ἀλλὰ λήγειν τῆς κακίας, ἵνα κατ’ ἄμφω εὐ- δόκιμος εἴη.