The foot is serious.

Feet are funny.

If you tell your friends, "My foot hurts," they cluck with sympathy.

If you tell them, "My feet hurt," they giggle.

Why is this?

Sing It, Fats

Up in Harlem at a table for two

Well, there were four of us baby--

Me, your big feet and you . . .

Your feet's too big.

Don't want you 'cause your feet's too big.

Mad at you 'cause your feet's too big.

I really hate you 'cause your feet's too big . . . Pedal Extremities

That was the late Fats Waller singing "Your Feet's Too Big," 1936, words and music by Ada Benson and Fred Fisher. The adult human foot contains 26 bones, 19 muscles and 107 ligaments, most of which hurt from time to time, and this is understandable when you consider the load they carry all day.

The average person walks about 65,000 miles in a lifetime, at a rate of 100 steps a minute. That is a lot of steps.

All sorts of things can go wrong with feet. You thought there were corns, bunions, ingrown toenails and athlete's foot, and that was it, didn't you. Well there are 75 ailments of the foot and 23 diseases with foot symptoms--congenital, nutritional, metabolic, traumatic and neurogenic.

An orthopedic survey shows that 7 in 10 elderly people have foot trouble, and 8 in 10 podiatry patients are women. This is because women buy a lot of shoes, especially high-heeled shoes. And when they buy them they try to fit not the foot but the eye.

Here we are, talking about shoes already.

Podiatrists say the big problem in talking about feet is that you always wind up talking about shoes. The Foot Soldiers

Dr. Jerome Shapiro of Washington is a podiatrist who can tell you plenty about feet. Podiatry, by the way, used to be called chiropody, from "chiro" (hands) and "pod" (feet). The first society was formed in 1895, the first school of chiropody in 1912. At the time a degree required one year of study beyond high school. Now you have to study four years beyond college and take a year or two residency.

They know a lot more about feet than they used to.

The name was changed to podiatry in 1955 because the doctors were specializing in feet only, and besides, they were tired of being confused with chiropractors.

Here's Dr. Shapiro:

"The soles of the feet are the thickest skin on the body and yet almost the most sensitive. They have more nerve endings per square inch than anywhere else except the palms."

This is because they were designed to sense the ground beneath them and react to bumps and pebbles and abandoned roller skates.

"They are also ticklish and are considered an erogenous zone," he says. "Women in particular like foot massage. So far no one has discovered a G spot in the foot, but its shape has been considered erotic in many cultures. One reason the Chinese bound women's feet was so that they would take tiny steps, moving the thighs in a way that was thought to be very sensuous."

Foot massage, incidentally, is a highly developed science whose practitioners say they find and treat places in your feet corresponding to various parts of your body and so can alleviate all sorts of ailments. Acupuncture, too, works with the sensitive spots on the feet to effect changes even in the personality itself.

Dr. Shapiro is also concerned with smelly feet. Every Christmas vacation podiatrists get visits from college freshmen. They are embarrassed, and they have made the appointment without telling their parents. At the end of the checkup it comes out: Their roommate has thrown them out because their feet smell. No one ever mentioned it to them before.

"You sweat in the summer," Dr. Shapiro says, "and sweat is how the skin gives off waste products, so sometimes it smells. So you take a shower. But your shoes don't take a shower.

"We wouldn't wear a leather suit in the summer, yet we wear leather shoes, which offer a moist, warm, dark place at body temperature--ideal for the growth of organisms. This is why we get athlete's foot but not athlete's hand."

One answer is to wear top-grain leather that has pores, and to use cotton or wool socks, not synthetics.

"We still have a lot to learn," says Shapiro. "Gout is caused by uric acid forming tiny crystals in the blood. Amazingly painful. Usually they collect at the great toe joint. Why there? We don't know." With Friends Like That

Bumper strip on a blue Peugeot wagon in the parking lot of the MacArthur Safeway:

YOUR FOOT IS YOUR FRIEND.

So which one? What's the matter with the other?

Mysterious. A Short History of Feet

Gorillas have flat feet. They do not like to walk much. Dr. Shapiro points out that the distance from heel to ball of foot is too short for a proper rolling heel-to-toe gait, so gorillas just slap their feet down splat. They walk like a skier doing herringbones.

"What happened when humans began to stand upright why was this? to see over the tops of that shoulder-high prehistoric pampas grass when they were hunting? was that their hands were freed up to develop various dexterous skills. Which led in turn to development of the brain. Also, the tongue sank into the lower jaw, so they could begin to speak.

"Over the generations, as they walked, the big toe moved closer to the others (because it was no longer needed for grasping tree branches) and grew longer. This made the foot more rigid and compact so it could act as a lever."

Basically, walking is an act of levering, rather like opening paint cans with a screwdriver except without the paint cans or the screwdriver.

Flat feet are an evolutionary defect, or atavism, he says, and so are bunions, which happen when the big toe doesn't move in with the others but sticks out there yearning for a vine to climb. Corns, on the other hand, are caused by shoes. The Saga of Corns

There's a mystery here. The first civilizations may have been Sumer and Babylon, going back to 4000 B.C., but so far we haven't found any mention of corns until the Ebers Papyrus of 1500 B.C. in Egypt.

Why not? Maybe they didn't wear shoes in Sumer? Certainly not high heels.

The Papyrus suggests olive oil and cow fat for corns, but evidently it didn't work all that well because it is not discussed by the Greeks, who preferred faith healing. Hippocrates, the father of medicine, did say that "if the skin be thick and hardened, it is to be pared down smoothly and thinned, but without wounding it."

Good thinking, Hippocrates.

Theophratus mentioned corns. He comes a century later, in 372 B.C. A pretty good corn plaster was invented by Hikesios of Smyrna, and Cleopatra had special servants who did nothing but work on her feet.

In the 1st century Pliny had this cure for corns and warts:

"Lie on your back along a boundary line on the 20th day of the moon and extend the hands over the head. With whatever thing you grasp when so doing, rub the warts and they will soon disappear. Also, if you pour vinegar on the hinge of the nearest door whenever you see a shooting star, your corns will go away."

In the Middle Ages, itinerant corn-cutters roamed Europe, eventually banding together in the guild of barber-surgeons, along with blood-letters and tooth-pullers. It was a David Low who in 1784 first thought of chiropody. He wrote a book about it: "Chiropodologia, a Scientific Enquiry into the Cause of Corns, Warts, etc."

There will be corns, one cynic says, as long as there are shoes. Celebrity Feet

* Abraham Lincoln wore size 14 shoes. He had so much trouble with his feet that he had a foot doctor in constant attendance at the White House. The specialist, Dr. Isachar Zacharie, was also a great friend who went on political missions for the president. Once he crossed the Confederate lines to try and arrange an end to the war.

* Robert Wadlow, who stood 8 feet 11, had feet that were 18 1/2 inches long. His shoe size was 37 AA. His heart gave out in 1940 from overwork.

* The playwright Aeschylus invented the platform shoe. It gave his actors that extra touch of authority onstage.

* Louis XIV was only 4 feet 11, so he wore elevator shoes. This made him as tall as everybody else in his court. The courtiers, who copied every move he made, started wearing tall shoes too. They were so uncomfortable that the in-word for feet at court was "mes chers souffrants," or "my dear suffering ones."

Of course, now that everyone else was wearing elevators, Louis was short again. It is tough to be a king. In Song and Legend

Whatever got into Cinderella to make her want to wear glass slippers? You look down and all you see is a bunch of swollen veins and a lot of toes jammed in like steerage passengers.

Put your foot down hard on a marble floor in an argument or a polka, and you send yourself to the hospital.

On a cement floor they would screech like fingernails on a blackboard. And blisters. Boy.

But the prince wasn't the only one stuck on feet. There was Gulley Jimson, the great untamed artist of the Joyce Cary books. He liked to paint feet. Big feet. He'd come to stay at your apartment, and next morning you would find he had painted a mural of God's Feet 10 yards long all across your walls. He couldn't help it.

But then, he was British. The British have always been extraordinarily interested in God's Feet.

"And did those Feet/ In ancient time/ Walk upon England's mountains green," sang William Blake. And of course, poor Francis Thompson in "The Hound of Heaven," pursued by "those strong Feet, that followed, followed after . . ."

The Old Woman Who Lived in a Shoe was, as we all know, a sly British reference to the Church of Rome, which is probably stretching the analogy. But now that we're into nursery rhymes, we should note that they are obsessed with feet, especially toes, or as the British say, piggies. "The Oxford Book of Nursery Rhymes" has page after page of piggy songs stemming from "This little pig went to market."

The ancient Roman foot was only 92 percent as long as our foot, which gave Gibbon some difficulty in translating all the distances in the Empire to modern terms. One assumes that the ancient Romans themselves were rather shorter than we. A few years ago the builders of Washington Cathedral ordered a platoon of stone saints--"lifesize," they insisted--from a sculptor in Italy. They arrived on schedule--but they were only 5 feet 1. All of them. The cathedral sent for the sculptor to see what he could do. He arrived on schedule too. He was 5 feet 1. "I Am Joe's Foot"

This 1970 Reader's Digest article has been reprinted untold thousands of times and still resides in innumerable podiatrists' waiting rooms. It has a lot to say. "The very best exercise Joe can give me is walking barefoot, as his ancestors did, over uneven terrain." It tells you how to order shoes ("at least half an inch longer than the longest toe") and how to treat ingrown nails, and it warns that "the great majority of older people have ailing feet from years of misuse. This is one of the main reasons they spend so much time in rocking chairs and on park benches."

So pay attention.

The human foot, Leonardo said, "is a masterpiece of engineering and a work of art."

It's really too bad we look down upon it so.