<p>Seattle Slew, the horse that won the Triple Crown in 1977, has died. So have the political ideas that were as dominant as he was 25 years ago.</p>
<p>Caught up in today's political battles, we forget how much the world has changed since then. Jimmy Carter was president. Tip O'Neill, whose political life began during F.D.R.'s New Deal, was speaker of the House. Despite Nixon's usurpation, everyone knew that Democratic control of the American government was permanent — as was communist domination of half the world.</p>