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
dē-circĭno: āre,
I v. a., to make of a circular form, to round off (only in Manil.): arcum, Manil. 1, 296: orbem, id. 3, 352.