An interesting passage from Edison’s Eve by Gaby Wood:
[Stefan] Zweig’s novella, The Royal Game, takes place at the outset of the Second World War on a boat from Europe to South America. One the boat is the reigning Russian chess champion, a man without finesse or intellect except in this particular domain. The narrator and a group of other passengers pay him to play against them; just as they are losing, a mysterious man intervenes on their behalf and leads them to a draw with the champion. The man, Dr. B., is urged to play a game one to one, but he says he has not sat at a chessboard for at least twenty years. He explains to the narrator that he came by his instinct for chess another way.
Imprisoned in an empty hotel room by the Nazis for months, with nothing to read or write with, in a cultural vacuum designed to make him submit to interrogation, Dr. B. had been beside himself. One day he discovered a book in the coat pocket of one of his captors and, hoping it would be Homer or Goethe, something he could memorize and learn from, succeeded in stealing it. To his great disappointment, the book was nothing but 150 championship games of chess, something he had not played since he was a student; but it was all he had. He began by improvising a chessboard and pieces with his bedspread and breadcrumbs he had saved; soon he could see it all in his head. Dr. B. found that learning the games sharpened his mind, but after some weeks he came to an impasse: he knew the games too well, and would have to invent new ones, playing against himself; but the division of his mind into two conflicting camps, “Ego Black” and “Ego White,” became too much for him–before long he was trapped in a chess fever, hallucinating, shouting, violent. He woke up in a sanitorium, suffering from what he calls “chess poisoning.” On being set free from there and from the Nazis, Dr. B. had been advised never to play chess again. Now, however, on the boat, he consents to one game — for this reason: he wants to “discover whether what went on in my cell was chess or madness.”