When Goodnight Moon was first published, in 1947, the chief children’s librarian at the New York Public Library didn’t like that its story—about a bunny’s bedtime routine that entails expressing well-wishes to various objects—was told from the perspective of a child, and refused to purchase it. (The institution didn’t carry the book, written by Margaret Wise Brown and illustrated by Clement Hurd, until 1972.) But Goodnight Moon’s honest presentation of sleep and solicitude still resonated with readers, who’ve since purchased more than 48 million copies of the title.