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
stubbornness: P. αὐθάδεια, ἡ, σκληρότης, ἡ, Ar. and V. αὐθαδία, ἡ.
cruelty: P. and V. πικρότης, ἡ, ὠμότης, ἡ, V. τραχύτης, ἡ.
