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
adj.
P. and V. δύσκολος, δυσάρεστος, ὀξύς, πικρός, Ar. and V. ὀξύθυμος, V. δύσοργος.
