What We Lose When No One Remembers the Girl with the Blue Eyes

A particular kind of YouTube video has, over the past few years, become a quiet refuge for millions of people who otherwise share nothing in common. The camera hovers above a wooden table. A pair of hands enters the frame holding a swab. A painting, cracked, yellowed, sometimes folded in half like a discarded letter, lies waiting. For the next twenty or thirty minutes, almost nothing happens, and yet everything does. The hands belong to Julian Baumgartner, and what he does, with the patience of someone defusing a bomb made of egg tempera and time, is listen to a stranger speak from across two centuries.I came to Baumgartner's videos the way most outsiders come to American subcultures: accidentally, then obsessively. A friend sent a link. I watched a portrait of a child, nameless, dated only by the cut of her collar, emerge from beneath a brown haze of varnish someone had applied, perhaps, by some well-meaning dealer in the 1920s. When the haze lifted, her eyes were blue. Someone,…