"To make a prairie,” Emily Dickinson once wrote, “it takes a clover and one bee, / . . . And revery.” But “the revery alone will do, / If bees are few.” To make a great literary biography it takes a great subject, a biographer’s understanding—and reverie. In the new biography of Eudora Welty by Suzanne Marrs the ingredients are all there. Marrs’s account of Welty’s life locates her essential loves and sheds light on the national, local and personal issues that wove their way into her fiction and essays.