"Alice began to laugh. "There's no use trying," she replied: "one can't believe impossible things.
"I daresay you haven't had much practice," said the Queen. "When I was your age, I practised for half an hour a day. Why, sometimes I've believed as many as six impossible things before breakfast. There goes my shawl again!" "
Lewis Carroll, Through the Looking-Glass, 1871
Among the countless puzzles and paradoxes, the following classic is perhaps the hardest of all to believe. Take a colourless chessboard made up of sixty-four squares and cut along the thick lines shown opposite. The challenge is to reassemble the four pieces into a rectangle.
