President Trump is criticized for things he has done, and for things he has left undone. It is possible to sin either way, of course, by action or by inaction; nothing unreasonable about that. What is unreasonable is the additional, arbitrary standard to which he, like all modern presidents, is held liable: what he has done, and left undone, in the first hundred days of his administration.

Trump’s health care bill crashed on takeoff, his tax reform hasn’t been seen, his executive orders on immigration were throttled by politically hostile judges—the list of setbacks is already, according to pundits, a litany of failures. Why? Because these top-drawer items were not signed, sealed, and delivered in the president’s first hundred days. Why is that important? Because the first hundred days are the most important days of all. And why is that? Because Franklin Roosevelt proved they are!

As though FDR doesn’t have enough to answer for, here is another of his legacies. No president before him had paid particular attention to the first hundred days after inauguration, since his four-year term of office had almost 1,361 more days to go. Why obsess about the initial 6.8%?

Besides, when in his July 24, 1933, fireside chat FDR spoke of “the hundred days which had been devoted to the starting of the wheels of the New Deal,” he