Spectacular Bid's goal on Saturday is not merely to win the Belmont Stakes and complete his sweep of the Triple Crown. "We're here to make history," trainer Bud Delp said this week.

The greatest challenge facing the gray colt will be posed by history rather than by the undistinguished rivals who are scheduled to face him. Spectacular Bid's performance will be measured against those great horses who have won the 1 1/2-mile classic, and in particular the three who have won the Triple Crown in this decade.

What would happen if those three horses reappeared in the peak form of their 3-year-old seasons, if Spectacular Bid's opponents on Saturday were Secretariat, Seattle Slew and Affirmed? this is what would happen:Seattle Slew breaks on top and jockey Jean Cruguet steers him immediately to the rail. Affirmed takes up the early chase as the field races to the first turn, while Spectacular Bidand Secretariat drop a half dozen lengths behind.

Entering the backstretch, Slew holds a one-length lead, but Affirmed is stalking him and Steve Cauthen has not yet asked him to make a move. Behind the leaders, Spectacular Bid is beginning to accelerate. Jockey Ron Turcotte doesn't want Bid to get away from him, so he chirps to Secretariat, telling him it is time to start running in earnest. Secretariat moves up outside Spectacular Bid.

After one mile, Slew is beginning to weaken, and Couthen asks Affirmed for a burst of speed, trying to open a sudden advantage on the field. But he can't. The two horses behind him are accelerating even faster.

Spectacular Bid and Secretariat are flying like a team. But jockey Ron Franklin, along the inside, sees that Seattle Slew is in his path. He can't get inside Slew, and he can't get outside Secretariat, who is abreast of him. Franklin has no choice but to put on the brakes, ease back and let Secretariat go past him.

When Franklin is encountering his difficulties, Secretariat moves up to challenge Affirmed. The battle for the lead is short-lived. Cauthen will say after the race that he saw only "a big red blur" going past him. Secretariat turns into the stretch with a two-length lead, as Spectacular Bid belatedly takes up the chase.

While Spectacular Bid steadily pulls away from Affirmed and Seattle Slew, he cannot gain any appreciable ground on Secretariat through the long Belmont stretch.

At the finish, Secretariat is the winner by two lenghts over Spectacular Bid, with Affirmed another three lenghts behind. Seattle Slew trails.

Comparing horses from different generations is, of course, a difficult exercise, but it is not impossibly speculative. I would base a comparison of the Triple Crown winners principally upon the times of their races, because this is the most precise measurement of a horse's ability. I would not pay much attention to the caliber of the opposition each horse beat; it isn't the horse's fault if his competition is weak. But I would take into account the visual impressions that the horses conveyed, and try to assess their versatility, competitiveness and other qualities that cannot be measured by cold figures.

Having seen all the Triple Crown races in this decade and analyzed the times of them in some detail, I am convinced that Spectacular Bid and Secretariat would have demonstrated clear-cut superiority over the other two horses. And the differences between them might have been determined by their jockeys.

Seattle Slew was the least impressive of the Triple Crown winners. He was a one-dimensional front-runner, and he didn't run especially fast. His time of 2.29 3/5 in the Belmont was atrocious.

Slew's apologists will point out that he proved his excellence as a 4-year-old when he defeated Affirmed twice. This is true, but Slew had improved with age, and with the more rigorous training he received during his 4-year-old campaign. As a 3-year-old, he was able to win the Triple Crown only because he was facing such dismal opposition.

Affirmed ran faster than Slew did in the Triple Crown races, and ran with much more flair. He showed great competitiveness and determination when he beat Alydar in their three memorable battles. But the deck had been stacked in Affirmed's favor. He was a speed horse in fields with no other speed, and so Alydar was forced to abandon his natural stretch-running style and play his opponent's game. When Affirmed had to cope with a speedball like Seattle Slew, he ceased to seem invinceble.

If ever a horse has looked invincible, it was Secretariat during the 1973 Triple Crown series. He shattered track records in the Kentucky Derby and the Belmont. And he won each of the races with panache.

He captured the Derby with a classic stretch run. He won the Preakness by circling the field on the first turn - and unprecedented feat. He took the Belmont after racing head-and-head with Sham through sim furlongs in 1:09 4/5 and running his archrival into the ground. He could cope with any situation, surmount any obstacle.

Spectacular Bid has not shown this kind of versatility; he seems to get into gear at about the same stage in all his races. But it is hard to tell whether this is due to the horse's lack of tractability or Franklin's inability to exert control over him.

It is also hard to judge just how fast Spectacular Bid is, because Franklin lost so much ground on the turns at Churchill Downs and Pimlico that he penalized the horse's performance by several lengths. Even with an optimal ride, he would still probably fall slightly short of Secretariat, but he would make it close CAPTION: illustrations, One man's idea of how a race between the cream of the decade's racing crop would shape up: Seattle Slew and Affirmed break on top, Slew holds lead after a mile but tires, Secretariat turns on gas and flies by Spectacular Bid and Affirmed and hits the wire a solid two lengths ahead of "bid," with Affirmed another three lengths back. By Alice Kresse - The Washington Post; Picture 1, Secretariat; Picture 2, Spectacular Bid: Picture 3, Affirmed; Picture 4, Seattle Slew