In 1998, a 13th century Greek Orthodox prayer book sold at auction at Christie's New York for $2 million. Why did it sell at such a high price? It's a palimpsest, an erased and overwritten document, and the true value of the book lays beneath the prayers, where one can make out the faint markings of a much older textthe only surviving copy of the essential works of Archimedes. The palimpsest had ... [more]