Bach's Brandenburg #3 came on the radio this morning on the way to school (does anyone else's kids tell them to turn their music down?) and the kids and I talked about how Bach had written the Brandenburgs for the Margrave of Brandenburg-Schwedt who, lacking the musicians to have them performed, basically stuck them in a drawer and forgot about them.
It occurred to me that the Margrave, had he had any sense of what had been given him, would have experienced great regret at never having heard them performed. But given that he was unaware of what he had, he had no regrets in that regard. I believe, however, that he should have. So is there a word for a regret that someone should have had, but didn't know that they should have had that regret?
I know that one can regret in advance and that that there is a word for something you wanted to know but then regretted knowing it. It's kind of the opposite of Lagniappe. I definitely feel proxy regret for the Margrave. But what do I call that which he should have felt?