A buyer has paid more than $136,000 (£94,000) for a letter sent by code breaker Alan Turing to his psychologist's daughter, which explains how to win at solitaire (not that solitaire - the board game, with marbles).
The letter, sent by Turing to eight-year-old Maria Greenbaum in 1953, was described by Boston-based auction house RR Auction as "exceedingly rare".
Turing used logic puzzles, such as solitaire and chess, as ways to demonstrate the potential capabilities of computers, the auction house said.
“I hope you may get this before you leave to morrow, as it will give you something to do in the train," writes Turing.
"It is just to tell you how to do the solitaire puzzle. I find it helps, if I am trying to do the puzzle to use four kinds of pieces like this or better still to use a board with the squares in four colours. Each piece always stays on the same colour until it is taken. You start with only four X's and you must still have [them] on at the end so you must be very careful of them. But there are 12 O’s to be got rid of. One needs to remember this all the time.”
"It's a handwritten private lesson in logic from the well-known British World War II code-breaking genius," said Robert Livingston, the company's executive vice president. We'll say.