ἰθεῖαν

From LSJ

κακοὶ μάρτυρες ἀνθρώποισιν ὀφθαλμοὶ καὶ ὦτα βαρβάρους ψυχὰς ἐχόντων → eyes and ears are poor witnesses for men if their souls do not understand the language (Heraclitus Phil.: Fr. B 107; Testimonia: Fragment 16, line 6)

Source

French (Bailly abrégé)

adv.
v. ἰθύς.

Russian (Dvoretsky)

ἰθεῖαν: adv. (sc. ὀδόν) по прямому направлению, прямо (ἰ. ἐς τὸν κόλπον Her.).