As news stories generally go, the retirement of a longtime member of Congress typically causes barely a ripple in the pool of politics. Unless the personage was a major power player or notorious for some other reason, our system of government treats the coming and going of most elected officials with only a modicum of interest. So it is likely to be with Senator Richard Durbin, Democrat of Illinois, who, having served seven terms in the House of Representatives and five in the Senate, announced he is retiring at the end of next year. The senator’s record in the overall...