Enchiridion · §51

πόσον ἔτι χρόνον ἀναβαλλῇ τὸ τῶν βελτίστων ἄξιον ἡγεῖσθαι σαυτὸν καὶ ἐν μηδενὶ τὸν διαιροῦντα λόγον ὑπερβαίνειν; παρείληφας τὰ θεωρήματα, οἷς σε δεῖ συμβάλλειν, καὶ συμβέβληκας. ποῖον οὖν ἔτι διδάσκαλον προσδοκᾷς ἵνα εἰς ἐκεῖνον ἀναβάλλῃ τὴν ἐπανόρθωσιν τὴν σαυτοῦ; οὐκ εἶ ἔτι μειράκιον, ἀλλ᾽ ἀνὴρ ἤδη τέλειος.ἐὰν τοιγαροῦν ἀμελήσῃς καὶ ῥᾳθυμήσῃς καὶ ἀεὶ προθεσμίαν ἐκ προθεσμίας ποιῇ καὶ ἡμέρας ἐπ᾽ ἡμέρας τίθῃς καθ᾽ ἃς προσέξεις σαυτῷ, λήσεις σαυτὸν οὐ προκόψας, ἀλλ᾽ ἰδιώτης διατελέσεις βιώσας καὶ ἀποθανούμενος.

poson eti chronon anaballē to tōn beltistōn axion hēgeisthai sauton kai en mēdeni ton diairounta logon huperbainein? pareilēphas ta theōrēmata, hois se dei sumballein, kai sumbeblēkas. poion oun eti didaskalon prosdokas hina eis ekeinon anaballē tēn epanorthōsin tēn sautou? ouk ei eti meirakion, all' anēr ēdē teleios.

How much longer will you delay thinking yourself worthy of the best, and refuse to transgress the reason that distinguishes good from bad? You have received the principles you need; you have accepted them. What kind of teacher are you still waiting for, that you keep postponing your own correction until they arrive? You are no longer a boy — you are already a fully grown adult. If you go on being negligent and lazy, making one delay after another and setting one day after another as the day when you will finally attend to yourself, you will live and die without ever making progress — you will remain an ordinary person to the last.

— Enchiridion 51

Source: Greek (Schenkl/Oldfather critical edition tradition) + Long 1877 English translation