Like all our political institutions, the presidency has evolved with the growth of the nation and the pace of change in the modern world. Three key changes come to mind.

Peter Schweizer has gotten lots of press on the charges in his just published book, Throw Them All Out: How Politicians and the Friends Get Rich Off Insider Stock Tips, Land Deals, and Crony Capitalism That Would Send the Rest of Us to Prison, that members of Congress made major moves in the stock market in response to information they received from top Treasury and Federal Reserve officials.

Governor Romney's defenders have argued that critics of his role at Bain Capital are really attacking capitalism itself. Given the academic evidence, we would have to agree.

The royal status the Kennedys temporarily achieved will seem bizarre to future generations--perhaps it already does even for those of us who can remember the 1960s.

Rather than await the decision on the Affordable Care Act, President Obama decided to attack preemptively with error-filled claims about the place of judicial review in our constitutional system. Judicial review springs from the duty of a court, when deciding a case before it, to enforce the Constitution over a conflicting act of Congress.

Half a century later, the Bay of Pigs is still the mother of all American military and foreign-policy disasters. It marks the start of America's bizarre habit of fighting our enemies with one arm pinned firmly behind our back, and dumping our friends when the going gets dicey. It also offers some pungent lessons for our current messes in Libya and Afghanistan.

While Ted Kennedy leaves the contemporary political stage, the man who served longer in the U.S. Senate than all but two others is now an indelible part of our political history.

Senator Ted Kennedy knew and expressed the sorrow of human life.