We need to remember that many words beginning with re-, such as reflect, return, and revert, do not need to be followed by back:
Even when I already know the story, I like hearing Grandma reflect back on her early days in this country. (Back is redundant.)
We decided to return back to our original itinerary. (Back is redundant.)
We need to guard against reverting back to the production problems that plagued us in June. (Back is redundant.)
Sometimes when we fall into redundancies, we are not just failing to write concisely. We are also failing to appreciate a word’s full meaning.
I heard a well-spoken political analyst use the phrase hearken back in a recent radio interview. Thinking he should have said hark back, I did a bit of research and discovered that what he said is fine. To hark is to recall, and the primary meaning of hearken (also spelled harken) is listen, but as often happens with words, the repeated use of hearken back to mean recall has become accepted.