IN 1983, ARTIST SOPHIE CALLE found an address book on a Paris street. Before returning it, she photocopied its contents, called the people listed, and asked to interview them about the book’s owner, whom she calls Pierre D. “I will try to discover who he is without ever meeting him,” she writes. Calle’s pursuit struck some—including Pierre—as a privacy invasion worthy of public retribution. He threatened to sue Libération

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