In the early stages of the 2016 presidential campaign, Ben Bernanke undertook a three-part essay, “What Tools Does the Fed Have Left?” It appeared on the Brookings Institution site. The economy was growing and creating jobs, the former Federal Reserve chair explained. The recovery, he thought, would surely continue. But at some point “in the next few years,” the economy might slow, he wrote – “perhaps significantly.” He asked, “How would the Federal Reserve respond in that case?” The first little essay discussed offering negative interest rates on government bonds. That means the purchaser would be paying for the privilege…