one must hear or hearken to, c. gen. pers., E. IA 1010, X. Smp. 3.9, etc. (also in pl. ἀκουστέα, Hdt. 3.61; τῶν κρατούντων ἐστὶ πάντ’ ἀκουστέα S. El. 340); c. acc. rei, Pl. R. 386a; abs., S. OT 1170.
one must understand, τι διττῶς Str. 9.5.12, cf. Gal. 15.484, Olymp. in Mete. 337.14; one must interpret, ὀνείρους Artem. 1.3.