Lewis & Short

prō-dŏcĕo, ēre, v. a., to teach before, i. e. to show by teaching, to inculcate (= docere altā voce et palam): haec Janus summus ab imo Prodocet, Hor. Ep. 1, 1, 55 (perh. imitation of the Greek προδιδάσκειν).