You have to remember in order to know you have forgotten
There is 1st & 2nd order memory: remembering that you do (or did) know the persons name, then remembering what it is
Or – what does flemp mean? I know that I do not know, & have never heard the word before
But I could well be embarrassed by being shown that I once used it in something I wrote. 3rd order memory?
Related posts: Known unknowns Compressing the Human Memory File