Δελφῖνα νήχεσθαι διδάσκεις: ἐπὶ τῶν ἐν ἐκείνοις τινὰ παιδοτριβούντων, ἐν οἷς ἤσκηται → Teaching dolphins to swim: is applied to those who are teaching something among people who are already well versed in it
γυιῶ (-όω) (Α)
1. καθιστώ κάποιον ανάπηρο
2. εξασθενώ, βλάπτω.
[ΕΤΥΜΟΛ. < γυῑον ή, κατ' άλλους, < (σύνθ.) απογυιώ («εξασθενώ, αδυνατίζω»)].