The Columbus Day just past afforded a taste of what's to come, as the United States prepares for the 500th anniversary of the discovery of America in 1992.

What we're in for is revisionism, the compulsive debunking of heroes. Op-eds and network television essays appeared Monday to inform us that, far from being a hero, Columbus was in truth a genocidal marauder, a greed-soaked mercenary and - lowest of blows - a lousy sailor.A few things should be set straight. The "plaster saint" image of Columbus is indeed oversimple; he was a man of his time, and then as now saints were rare. Christopher Columbus is nevertheless a massive figure in the history of civilization, the actual and symbolic link between the Old World and the New, whose lonely and heroic effort was the seed from which flowered what we know today as the United States.

Maybe that's what bothers the debunkers. Some of them seem to have a distaste not just for Columbus but for the American enterprise itself, in which case his debunking is merely the means to a larger slander. Let the buyer - and the magazine reader and the TV watcher - beware.