"And, naturally, the undone is the unfinished..."

My brother reminded me tonight about a sentence I had to edit in someone's college paper.  I've forgotten the assigned topic, but all these years later, I still remember the author's cryptic sentence, "Of course, the unseen is the unknown, and the unknown is usually the unexplained, therefore being difficult to imagine."  I've forgotten how I edited it; most likely, I asked the author to delete the sentence.  Then again, I might have written, "What????????," in the margin.

I imagine many teachers would have reacted similarly.