There Is Simply Too Much to Think About: Collected Nonfiction by Saul Bellow Viking, 2015, 532 pages, $43.50   Authors like Les Murray and David Malouf read a lot, and as a result produce stimulating essays. Saul Bellow, the best American novelist of the past half-century, confesses, “I am of course an auto­didact, as modern writers always are,” and this posthumous selection of essays puts him among the best commentators too. As the book’s title explains, we are today so bombarded by foreground chatter, crises, information overload and media blitzes that we’re constantly distracted: “Each of us stands in the…