late 12c., from Old English *heorcian, perhaps an intensive form from base of hieran (see hear). Cf. talk/tale. Cognate with Old Frisian harkia "listen," Middle Dutch horken, Old High German horechon, German horchen. To hark back (1829) originally referred to hounds returning along a track when the scent has been lost, till they find it again. Related: Harked; harking.
Return to a previous point, as in Let us hark back briefly to my first statement. This expression originally alluded to hounds retracing their course when they have lost their quarry's scent. It may be dying out. [First half of 1800s]