“Is it okay,” I asked, “to put my hand here?” “Here” was Jesus’ brown hair, on a 700-year-old fresco of the crucifixion, in a cave church in Puglia, Italy. In the fresco, Jesus’ eyes were depicted as closed, giving the portrait an oddly serene feel. My task at the moment was to use a scalpel to scrape away calcium deposits on the right eye (a spider was sitting on the left one), and I needed to ground my hand on the fresco to get good leverage. Tonio Creanza glanced over from the fresco he was working on. “Sure,” he said.

So I started scraping. That someone like me — well-meaning but completely untrained and unskilled — would be applying a razor-sharp instrument to an ancient treasure is due, entirely, to Creanza, a 50-year-old George Clooney look-alike who hails from the Puglian town of Altamura. In 1989 he launched a summer workshop designed to bring in volunteers to work on preserving and celebrating some of the treasures of his native region.