hark back

Hark, a very old word meaning "listen," was used as a cry in hunting. The master of the hunt might cry "Hark! Forward!" or "Hark! Back!" The cries became set phrases, both as nouns and verbs. Thus, a "hark back" was a retracing of a route by dogs and hunters, and "to hark back" was to turn back along the path. From its use in hunting, the verb soon acquired its current figurative meanings. In the early 20th century, English speakers began using "hearken back" and its variant "harken back" synonymously with the verb "hark back." (Like "hark," "hearken" and "harken" can mean "listen.") And since the 1980s, there's been another development: "harken" can now be used alone to mean "hark back."