In his speech to Achilles in Iliad 9, Phoinix laments the idea that he may be separated from Achilles. Part of his sorrow, it seems, resides in the fact that he has work still to do (437-443):

“How could I be left here without you, dear child,
alone? The old man and horse-trainer Peleus assigned me to you
on that day when he sent you from Phthia with Agamemnon
still a child, not yet educated in the ways of crushing war
or assemblies where men become most prominent.
He sent me for this reason: to teach you all these things,
how to be a speaker of words and a doer of deeds.”

πῶς ἂν ἔπειτ’ ἀπὸ σεῖο φίλον τέκος αὖθι λιποίμην
οἶος; σοὶ δέ μ’ ἔπεμπε γέρων ἱππηλάτα Πηλεὺς
ἤματι τῷ ὅτε σ’ ἐκ Φθίης ᾿Αγαμέμνονι πέμπε
νήπιον οὔ πω εἰδόθ’ ὁμοιΐου πολέμοιο
οὐδ’ ἀγορέων, ἵνα τ’ ἄνδρες ἀριπρεπέες τελέθουσι.
τοὔνεκά με προέηκε διδασκέμεναι τάδε πάντα,
μύθων τε ῥητῆρ’ ἔμεναι πρηκτῆρά τε ἔργων.

A Scholiast (Schol. bT in Il. 9.443 ex 1-4) suggests that what Achilles needs to have learned is “rhetoric” (φαίνεται οὖν καὶ τὸ τῆς ῥητορικῆς ὄνομα εἰδώς) whereas another scholion (Schol. AT in Il. 9.443 c1) emphasizes the fact that the execution of both deeds and words requires “good counsel” (εὐβουλία: σημείωσαι ὅτι τὸ ὁμοιοτέλευτον ἔφυγε μεταβαλὼν τὴν φράσιν· οὐ γὰρ εἶπε ‘μύθων τε ῥητῆρα καὶ ἔργων πρακτῆρα’. καὶ ὅτι πάντων διδακτικὸν εὐβουλία).

This passage is popular in later antiquity as well, where Plutarch cites it several times. He uses it almost in passing in discussing whether or not the elderly should rule the state:

An seni respublica gerenda sit, Plutarch, 795e5-796a7
“It is not possible for the overseer to contend for a prize when others are competing; and the one who trains the youths in common affairs and public contexts prepares them for their country: “To be speakers of speeches and doers of deeds”, which is useful in no small or minor part for a government: for this reason first and foremost, Lykourgos exerted himself to make sure that the youths obeyed every elder as if he were a law-giver.”

τὸν μὲν γὰρ ἐπιστάτην ἀθλοῦσιν ἑτέροις οὐκ ἔστιν αὐτὸν ἀθλεῖν, ὁ δὲ παιδοτριβῶν
νέον ἐν πράγμασι κοινοῖς καὶ δημοσίοις ἀγῶσι καὶ παρασκευάζων τῇ πατρίδι

μύθων τε ῥητῆρ’ ἔμεναι πρηκτῆρά τε ἔργων

ἐν οὐ μικρῷ μέρει πολιτείας οὐδὲ φαύλῳ χρήσιμός ἐστιν, ἀλλ’ εἰς ὃ μάλιστα καὶ πρῶτον ὁ Λυκοῦργος ἐντείνας ἑαυτὸν εἴθισε τοὺς νέους παντὶ πρεσβύτῃ καθάπερ νομοθέτῃ πειθομένους διατελεῖν.

In the Pseudo-Plutarchean Life of Homer, these lines are used to assert (1) that virtue is teachable and (2) that Homer was the first philosopher (Ps-Plutarch Vita Homeri 1736-1739):

“For life is sustained by means of actions and words, and he says that he was made a teacher of the young man about both. From these lines he asserts clearly that every kind of virtue is teachable. Thus Homer was therefore first to philosophize concerning ethical and natural affairs.”
ἐπεὶ γὰρ ὁ βίος ἐκ πράξεων καὶ λόγων συνέστηκε, τούτων φησὶ διδά-
σκαλον ἑαυτὸν τοῦ νεανίσκου γεγονέναι. ἐκ δὲ τῶν εἰρημένων δῆλον
ὅτι πᾶσαν ἀρετὴν ἀποφαίνει διδακτήν. οὕτω μὲν οὖν πρῶτος ῞Ομηρος
ἔν τε ἠθικοῖς καὶ φυσικοῖς φιλοσοφεῖ.