ὀχετός
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
English (LSJ)
ὁ, (ὄχος, ὀχέω)
A means for carrying water, water-pipe, made of leather, Hdt.3.9; when carried underground, sts. of wood, IG12.373.64, 66,22.1672.305; of stone, ὀ. λίθινος κρυπτός ib.7.4255.5 (Oropus, iv B. C.); material not named, Th.6.100, Pl.Phd.112c, etc.; τοὺς προϋπάρχοντας ὀ. κρυπτοὺς ποιεῖν OGI483.74 (Pergam.); conduit, channel, Arist.Pol.1303b13, al.; ὀ. μετέωροι open drains, Id.Ath.50.2, OGI483.63 (Pergam.); = ἀφεδρών, Ev.Marc.7.19 (cod. D). 2 in Anatomy, τῆς ἀρτηρίας ὀχετοί ducts leading to the lungs, Pl.Ti.70d; οἱ τοῦ αἵματος ὀ. Poll.2.217; of the urinal and intestinal canals, Hp. Art.48, 50, X.Mem.1.4.6; ὥσπερ ἐξ ὀχετῶν (of sweat), Hp.Epid.6.3.1. II in pl., streams, Pi.O.5.12; Σιμούντιοι ὀ. E.Or.809 (lyr.), IA 767 (lyr.). III metaph., βαθὺς ὀ. ἄτας Pi.O.10(11).37; παρεκτρέποντες ὀ. ὥστε μὴ θανεῖν making a side channel or means of escape, E. Supp.1111; ὀχετοὶ βοτρύων pherecr.130.7, cf. Telecl.1.9; ἐν τοῖς μεριστοῖς ὀ. currents, Dam.Pr.127, cf. 130, 206. IV Att. for βόρβορος acc. to Hellad. ap. Phot.p.535 B.
