There is an arresting moment in Walter Isaacson’s biography of Steve Jobs in which Jobs speaks at length about his philosophy of business. He’s at the end of his life and is summing things up. His mission, he says, was plain: to “build an enduring company where people were motivated to make great products.” Then he turned to the rise and fall of various businesses. He has a theory about “why decline happens” at great companies: “The company does a great job, innovates and becomes a monopoly or close to it in some field, and then the quality of the product becomes less important. The company starts valuing the great salesman, because they’re the ones who can move the needle on revenues.” So salesmen are put in charge, and product engineers and designers feel demoted: Their efforts are no longer at the white-hot center of the company’s daily life. They “turn off.” IBM and Xerox, Jobs said, faltered in precisely this way. The salesmen who led the companies were smart and eloquent, but “they didn’t know anything about the product.” In the end this can doom a great company, because what consumers want is good products.