Horses can not be taught to sit up and beg, as dogs and politicians so easily do, and so a lot of people at the 108th Kentucky Derby believe horses are dumb. But the fact is that rarely has a horse gone out in public wearing his sister's pajamas under his father's marriage coat.

Dwight McGuire, on the other hand, thinks his sister's blue and white striped, toe-to-neck, terry cloth 'jammies with the cute lace are the keys that will unlock the sort of fame heretofore reserved for geniuses with kaleidoscopic hair.

Heirs to the human majesty of da Vinci can be found everywhere, but the most remarkable bearers of the torch come to Churchill Downs the first Saturday of every May, when they gather in splendid communion on the infield grass to share T-shirt wisdom such as, "Feeling low as a belly-gunner on an armadillo."

"If I come out in my sister's 'jammies here and at the Indianapolis 500, maybe I can get TV exposure like that guy with the orange and blue hair," said McGuire, 24, of Jeffersontown, Ind., who said his white tux coat is the one his father wore to his marriage. "The rest of this stuff (white top hat, white gloves, basketball sneakers, sunglasses, polka-dot bow tie) is just what I had laying around."

Before we finish this tour of Americana on display, we will move from the first stratum of Derby society, in which a guy pulls along a little plastic horse on wheels, to the sixth floor of the majestic Churchill Downs grandstand, there on "Millionaire's Row" where governors call out to Barbara Walters, only to go unanswered.

Secretariat, to name a horse, never was seen pulling along a little human doll on wheels, but at noon today Tim Clancy, 17, of Rock Island, Ill., moved bare-chested through the thousands of getting-naked college kids with his little horse doll on wheels clattering along behind him.

"His name is Dodge," Clancy said. "He goes everywhere with me. I took him to the mall for his birthday and we had pizza."

The horse's breeding, sir?

"I got him out of my garbage can."

The elastic industry is taking a beating, if a casual inspection of women's wear in the infield is to be believed, but the gross national product is likely propped up by an equation that suggests an inverse relationship between clothes worn and liquor and/or drugs consumed.

"FBI, FBI," shouted Dave Butsch, frightened by the approach of an ordinary sportswriter wearing a tie and matching shoes. "We ain't got no drugs. Honest."

Now, from the infield we intrepid sociologists move up to the third-floor clubhouse level, where box seats come marked with old-money names (Polk Laffoon III, Rexburg Rennie, Duvall A. Headley) who have ponied up as much as $1,000 a seat for the right to wear preppie pastels within actual sight of an actual horse (infielders see a microsecond of a blur, if that).

"I would love, very much, to win Indianapolis again," said four-time winner A.J. Foyt, who owns 30 race horses and, at this moment, holds a fistful of losing tickets in the high-roller's bar, "but my racing days are about over. I'm venturing into a new field of racing, and I'd like to be tops there, too."

"In the Super Bowl," said quarterback Ken Anderson of the Cincinnati Bengals, wearing a pink jacket, "we're out there to do a job, we're not after fun in the sun. Here, as a fan you can stay out all night and drink."

The world's self-proclaimed greatest ticket scalper, who shall be known here only as Ducksy, an endearment derived from the word ducats, said this hasn't been a good year for Derby business. "The economy's off. You go to get your money, and the high rollers are busted. Builders and bankers are tapped out. But the fast-lane guys are still okay."

Kentucky's senior U.S. Senator, Wendell Ford, who stood crowd duty as a national guardsman at the 1950 Derby, said he first came to the race with his father "when the men wore straw hats and the women wore furs." Ford isn't sure what the magic of the Derby is, but says, "If people pay out $10 a night to camp in a yard and not see a single race, there has to be something there."

Riding up the elevator to the millionaires' aerie, from which the rich look down on the infield masses, a Kentucky state trooper said, "That Playboy bunny (January's issue, guys) said to a trooper, 'Take off your clothes.' He gave her his hat. You'll see the picture in the paper. He's the only trooper without a hat."

Big cheeses from ITT and Time Inc., and oil barons and actresses and country singers and senators and fried chicken magnates cozied up to mint juleps at tables around Kentucky Gov. John Y. Brown Jr., who called out to Barbara Walters, "Barbara, Barbara," only to give up when the famous interviewer went on talking to someone.

"I'm like a prize bull this week, they just lead me to where they want me," Brown said, deferring all honor for today's 15,000-person breakfast to his wife, Phyllis George. "All I know is that this week is unique. In the press and everywhere, people dwell on the negative, the cynical. But here there are positive things and warmth that happens nowhere else.

"Kentuckians go all out to make this a special place, and there's no week like Derby Week."

It's your sister's 'jammies, is what it is.