A conservator responsible for a seventeenth-century altarpiece once turned down a client's request to erase a long crack that ran through the painted sky above the central figure. She explained that the crack, caused by decades in a damp sacristy, had become part of what the painting now was: to fill it seamlessly would produce a physical object that looked older than the varnish suggested but felt, paradoxically, less honest about its own age. Her job, she said, was not to return the painting to a moment that could never really be recovered, but to keep visible the entire life the object had lived since it left the artist's hand—including the years that had not been kind to it.