A century after your death, what traces of your life will remain? Perhaps someone might find discarded clothing or a few boxes’ worth of cherished effects: china, jewelry, a watch, a toy. Your signature on official forms may linger, along with plenty of photos, likely in an outdated file format. What will these scattered items say about you? Even if everything from your time on Earth—every letter, text, tax filing, piece of furniture, and knickknack—were to be preserved, would you be confident that a researcher drawing on your personal archive could accurately describe the kind of person you were, or understand the life you led? Would you want them to speak for you?

Now consider how little of consequence actually survives the churn of human affairs. Mold eats away at diaries and letters. Technological failures and fires swallow family photos. . . The constellation of small things that make up a life is blown apart so easily that historians, biographers, and archivists make accounting