A prisoner was isolated in a cell with nothing but a cot, a chamberpot and a footlocker. It was a mystery to him why he was given a footlocker. He had nothing to put in it except one change of underwear and a spare pair of socks.

He had nothing to do all day except dream of escape. How this could be accomplished was even more mysterious, for there was no door or windows in his cell, just six inner surfaces — six directions teasing infinite extension, halted by impassable cinderblock.

He did not know how thick the cinderblock walls were. Dayless and nightless eternity, stretching onward without end, but without access to future or past, persuaded him that the cinderblock extended infinitely in all directions.

One day the two mysteries — the inescapable cell, the pointless footlocker — became one, and he had his answer. The prisoner climbed into his footlocker, closed the lid and achieved the impossible.