Besides the Opera, I can only find it to be a male name (from Old French, meaning "pierce" and "valley") and from Parsifal in Teutonic legend. I can't find anything about "simple fool," unless that was part of the opera or the Teutonic legend. Does anyone else know?
Kalleh, I'm aware that the Parsifal legend states that only one who is pure, unsullied by the world, can find the grail, so I suspect that "simple fool" had the meaning of "unsullied." However, I can find no support for my guess.
