“It is clear that the need for innovation has never been greater,” my old Economist colleague (and friend) Vijay Vaitheeswaran writes in his new book Need, Speed, and Greed. It may be clear to Vijay, but it’s not at all to me: The need for innovation in World War II, or the Irish potato famine, or in ending slavery, or at pretty much any randomly selected point in time in the past strikes me as about the same as its necessity today. Vijay’s case rests on the argument that we live in conspicuously heady times, an argument that is made by assertion. He goes on to say that “new ideas move to market faster than ever before.”

But can we meaningfully measure the speed with which new ideas move to market? Alexander Graham Bell filed his patent for the telephone in February 1876. By April 1877, the first commercial telephone lines were being installed. Of course you can cherry-pick examples to show greater or slower speeds.