"Mr. Humes, a Pulitzer Prize winner in 1989 for articles about the military, tells how Jib Ellison, a onetime California river-rafting guide, all but singlehandedly persuaded Wal-Mart to embrace sustainability as part of its core culture. Starting with a meeting in 2004 with H. Lee Scott Jr., then Wal-Mart’s chief executive, Mr. Ellison demonstrated that sustainability wasn’t just tree-hugger talk. In its simplest form, sustainability means eliminating waste. And eliminating waste saves money. That got Mr. Scott’s attention."