A familiar figure in American politics for the last 20 years bowed out last week, and hardly anybody paid attention.

Nelson Rockefeller got less notice when he announced his decision (after four terms as a governor, three presidential campaigns and a brief career as vice president) than he got back in 1954 when reporters began to guess out loud whether he might run for mayor of New York City.

Rockefeller has been my friend since long before that year, so you may discount to whatever extent you wish my opinion that he was the best thing the Republicans had going for them since Wendell Willkie.

And you may laugh at that. But if you're old enough to remember that Willkie gave Franklin Roosevelt a good race, you may also remember that he was a Republican in the Teddy Roosevelt tradition, an activist, mildly infected with the reform spirit, a strong believer in capitalism on the assumption that it should be and could be both responsible and creative.

Unlike Willkie's, Rockefeller's political career began during the era of anti-communism and so he had to worry about whether innovation might be labeled as "pink." But considering that he launched himself at the height of McCarthyism and that he did so as a Republican, he handled admirably the problems of individual rights and civil liberties that McCarthy posed.

Still, the persistent notion that he was a secret left-winger dogged Rockefeller throughout his career. True, it led to his finest hour: that great speech in San Francisco made over the rude and raucous jeers of the Goldwater delegates at the Republican convention of 1964. But he spoke as a loser.

I don't think Rockefeller ever figured out why the conservative wing of his party hated him so, even after a careful reading of the polls convinced him that he himself ought to become a conservative. And even after he ran two consecutive New York gubernatorial races as though he were Mr. Conservative.

That was not so false a pose as people thought at the time. Rockefeller really is a conservative. But his conservatism is tinged by the sophistication of civil libertarianism. Were some of the artists he admired communists? They were, nevertheless, good artists. And touched also by his almost fervid belief that capitalism ought to be an active, expanding force, and that only as such does it scatter benefits to society.

It says a lot about the Republican Party from the days of the Birch Society to the days of the New Right that a belief in civil liberties (or maybe in artists) and a conviction that capitalism is innovative should be regarded as too much to swallow.

Rockefeller was too open-minded for the zealots who followed Goldwater. He actually saw some good in examining other people's ideas. And he was too human for the ice-cold Nixon crowd. He permitted himself, perhaps too often, to be a man instead of a politician.

That, of course, is one reason he never reached the top. He probably could have beaten John Kennedy in 1960. At least Kennedy always thought so. But Rockefeller fell in love. And he might have beaten Goldwater in 1964, but on the eve of the California primary he reminded everybody of the love affair by becoming a father.

Indeed, many of the mistakes Rockefeller made in New York were mistakes of the heart. He wanted to do too much, too quickly, for too many. On the other hand, nobody will ever say about Nixon that his mistakes were of the heart.

So I think the Republican Party will miss Rockefeller. He stirred it up; he infuriated it - and therefore he helped to keep it alive.