“Art is confession; art is the secret told,” Thornton Wilder wrote shortly after fame and the first of his three Pulitzer Prizes had come to him in his early 30s. “But art is not only the desire to tell one’s secret; it is the desire to tell it and hide it at the same time.” That suggestive formulation is as evocative today as it was when Wilder penned it in 1928. But now we are more likely to associate specific literary genres with the heart’s hidden truths: the ever-billowing genre of memoir is confession, we might say, and biography is the secret told......