As the popularity of thoroughbred racing has declined and the economic health of the industry has suffered in recent years, nobody has done much about it. People in the sport tend to be more concerned with parochial interests, rivalries and ego conflicts than with the industry's overriding problems.

But just suppose that somebody came along with an idea -- a bold, visionary idea -- that would remedy many of racing's current ills. What would happen? Now we know: the idea would promptly be engulfed by parochial interests, rivalries and clashes of egos.

The man who conceived the Big Idea was John Gaines, one of the most prominent figures in the Kentucky breeding business. Gaines recognized, as most people have, that while breeders are prospering, selling $4 million yearlings and syndicating $36 million stallions, purses for races have not kept pace even with inflation.

Gaines understood, too, that the lopsided economics of the thoroughbred business were having some unfortunate consequences. Good horses were being campaigned sparingly and rushed off to stud prematurely, because that was the only way to make big money. As a result, racing was losing its box-office attractions.

Gaines' solution to this problem was breathtaking. He proposed to stage a one-day racing extravaganza with rich championship races for all major categories of horses, topped by a 1 1/4-mile race for 3-year-olds and up with a colossal purse of $4 million.

Individual tracks don't have the resources to offer such purses, so Gaines proposed that the breeding industry foot the bill. To nominate a stallion's offspring for the Breeders' Cup races, his owner would pay a sum equal to his stud fee. Affirmed stands for a $125,000 fee, so Spendthrift Farm would have to pay this amount to make Affirmed's sons and daughters eligible for the races.

But when the Breeders' Cup executive committee was formed, rivalries and conflicts developed immediately. Gaines is not a popular man; he is considered a tough customer even by the standards of his cutthroat business. He can be opinionated and overbearing, and even when he was dealing with a committee comprised of some of the richest and most powerful men in the sport, he insisted on running the show.

The first big split on the committee came over an argument about the way the money contributed by breeders would be used. Many board members wanted to use half of it to augment the purses for established stakes races around the country. Gaines clung to his vision of the one-day extravaganza.

Then the committee heard presentations from tracks that wanted to stage the Breeders' Cup. The California tracks, Hollywood and Santa Anita, made an impressive pitch and the West Coast was awarded the first Breeders' Cup in 1984. The committee said that the 1985 edition would be held in the East, either at Belmont Park or the Meadowlands, but that decision enraged members of the Eastern racing establishment. Dinny Phipps, chairman of the New York Racing Association, was especially outraged, and so was the breeder with whom he is associated, Seth Hancock of Claiborne Farm. Hancock and three other committee members quit.

This was a significant defection, because some of the world's most prominent stallions -- Nijinksy II, Secretariat, Conquistador Cielo--stand at Claiborne. If Hancock didn't participate, other breeders probably would conclude that this venture was not worth supporting. Gaines knew his grand vision was in trouble, and that he was a principal reason. So he stepped down from the presidency of the Breeders' Cup; his executive director resigned; some of the defectors rejoined the committee, and a measure of harmony was restored.

And then the money started coming in. Gaines, of course, nominated all his stallions to the series. Then Spendthrift Farm spent more than $1 million to nominate all its stallions, with its vice president, Arnold Kirkpatrick, saying, "The bickering is over. This Breeders' Cup is going to fly."

Hancock still had not yet nominated the Claiborne stallions, but by last week the Breeders' Cup had already collected more than $6 million, enough to ensure that in 1984 the sport of thoroughbred racing will undergo its most revolutionary change in years, and that John Gaines' grand vision will become a reality.