I used to think that you could spot a literary classic by identifying certain salient characteristics: the writing would need literary quality, for example; the book would have had some historical significance; it would have an enduring reputation among scholars and general readers. But each rule threw up exceptions. Darwin’s The Origin of Species is not an obviously ‘literary’ text. E.M. Forster’s Maurice was first published six decades after it was written. The Song of Kieu, the greatest work of Vietnamese literature, is virtually unknown outside Vietnam. And yet all of these books are classics. Over time I have come to agree with Ezra Pound’s warning at the start of his ABC of Reading (1934). ‘A classic is classic not because it conforms to certain structural rules, or fits certain definitions (of which its author had quite probably never heard),’ he writes.