“Several Old Master paintings have turned up just this year. In July, two frescoes in the Vatican thought to be the work of Raphael’s students were determined be by the master himself. In October, a New Jersey town announced that a bust of Napoleon Bonaparte, on display for over 80 years in the council chambers of a local borough hall, was actually a long-lost work by Auguste Rodin.” Why are we only discovering them now? Partly, it’s because of newly-available technology, and partly it’s – well, it’s dirt.