In Edward Winter’s Chess Explorations there is the following delightful quote from the memoirs of chess player William Winter:
Blindfold play I have never attempted seriously. I once played six, but spent so many sleepless nights trying to drive the positions out of my head that I gave it up.
I love that. We think of the difficulty as being in the remembering, but maybe it is the forgetting that is the challenge. I’m reminded of a lecture I saw by Richard Feynman at Bell Labs: He was talking about the theoretical challenges of quantum computing, and he identified the crucial entropy-producing step as that of zeroing the machine, i.e. forgetting.