Former Attorneys General Eric H. Holder Jr. and Michael B. Mukasey at The Washington Post:

Our system can accommodate even ill feeling, and it has. Our second president, John Adams, famously left Washington in 1801 before Thomas Jefferson was sworn in as the third. Closer to our own time, although Herbert Hoover attended Franklin D. Roosevelt’s inauguration in 1933, their mutual dislike had hardened so much that few if any words were spoken between the two men during the ceremonial ride to the Capitol.

The critical point is that Adams and Hoover accepted the outcome of the elections they lost. In Adams’s case, enmity turned to friendship: Adams and Jefferson later grew so close that as Adams lay on his deathbed on July 4, 1826, ignorant of Jefferson’s death on the very same day five hours earlier, he comforted himself with the words, “Thomas Jefferson survives.” By contrast, Hoover and Roosevelt never repaired their relationship. No matter. Good feeling between political adversaries isn’t necessary to permit our system to function; acceptance of results is.