Ezra Pound turns up five times in Peter Gay’s big survey of the modern movement in literature and the arts, “Modernism: The Lure of Heresy”—once in connection with T. S. Eliot’s “The Waste Land” (which Pound edited), once as the author of an anti-Semitic sentiment (one of many), and three times as the originator of the slogan “Make It New” (which suits the theme of Gay’s account). Pound’s poetry and criticism are not discussed; no reader of Gay’s book would have any idea of what his importance or influence as a writer might be. Gay’s is a commodious volume with a long reach, “From Baudelaire to Beckett and Beyond”; still, a handful of passing references seems a sharp decline in market value for a writer who was once the hero of a book called “The Pound Era.”...