Go here for more information about Ancient Greek collections of proverbs.
“Milk nourishes infants and conscious children, milk fattens like wisdom”
Γάλα τρέφει νήπια, παῖδα δ’ ἔμφρονα, γάλα πιαίνει σωφροσύνη καθάπερ.
[I want the last phrase to go the other way, e.g. “wisdom fattens like milk” but I can’t justify it completely]
“Whatever love you bear for your parents expect the same kind in old age from your children”
Οἵους ἂν ἐράνους ἐνέγκῃς τοῖς γονεῦσι, τούτους αὐτοὺς ἐν τῷ γήρᾳ παρὰ τῶν παίδων προσδέχου Πιττακοῦ.
“The doors of the muses are open”: a proverb applied to those readily acquiring the best things in their education.”
᾿Ανεῳγμέναι Μουσῶν θύραι: ἐπὶ τῶν ἐξ ἑτοίμου λαμβανόντων τὰ κάλλιστα τῶν ἐν παιδείᾳ.
“Teaching dolphins to swim: [this proverb] is applied to those who are teaching something among people who are already well versed in it.”
Δελφῖνα νήχεσθαι διδάσκεις: ἐπὶ τῶν ἐν ἐκείνοις τινὰ παιδοτριβούντων, ἐν οἷς ἤσκηται.
Michael Apostolios 6.27
“Old men are children twice: A proverb used for those who seem rather simple as they approach old age.”
Δὶς παῖδες οἱ γέροντες: ἐπὶ τῶν πρὸς τὸ γῆρας εὐηθεστέρων εἶναι δοκούντων.
“Neither swimming nor letters: thus proverb is applied to those who are unlearned in all regards. For the Athenians were taught swimming and reading from childhood.”
Μήτε νεῖν μήτε γράμματα: ἡ παροιμία ἐπὶ τῶν τὰ πάντα ἀμαθῶν· οἱ γὰρ ᾿Αθηναῖοι εὐθὺς ἐκ παίδων κολυμβᾶν καὶ γράμματα ἐδιδάσκοντο.