Three years before Alan Greenspan was born, John Maynard Keynes published his most-quoted line: “In the long run we are all dead.” It’s not just by touching the grand age of 100 before departing on Monday that Greenspan lived up to the quote’s promise. Keynes wanted economists to comment reliably on the present, not bloviate post facto. Greenspan, who chaired the US Fed for 18 years, was a master at that. His gnomic utterings were so eagerly anticipated that Wall Street devised a ‘Briefcase Indicator’—the thicker Greenspan’s leather briefcase going into a rate-setting meeting, the higher the chance of a hike. His most astute advice to central bankers came in what he said to a US Senate Committee: “If I seem unduly clear to you, you must have misunderstood what I said.”