The mustard seed has ancient and impeccable credentials.Hippocrates used it as medicine as early as 440 B.C. In the New Testament, the Kingdom of Heaven is likened to a grain of mustard seed, which indeed is the least of all seeds, but when it is grown, it is the greatest among herbs, and becometh a tree, so that the birds of the air come and lodge in the branches thereof . (Matthew 13: 31-32)

More modern testimonials have come from Winston Churchill, who refused to put fork to roast at a White House dinner during World War II until the mustard pot was brought. Sometime later, Marlene Dietrick sang about it as a synonym for male potency, in a voice rather like the best mustard, soft and silky with delightful little roughages along the way: He's too old to cut the mustard any more .

And for all the centuries between Hippocrates and Dietrich, mustard has stood on its own strong feet as a force of public benefit and gustatory pleasure.

Before the time of antibiotics, ground mustard, mixed with flour and water, poulticed the chests of sufferers from pneumonia, influenza, bronchitis and other respiratory ailments. Its action reddened the skin, stimulating circulation, it was hoped, to the organs beneath.

In hot packs it soothed the pains of arthritis, rheumatism, bursitis and the general collywobbles of joints. Steeped in basins of hot water, it soaked chilled feet to prevent or treat the common cold. Mixed with oils it become a liniment for muscle aches and sprains.

Asthma victims were offered a few sniffs of the mustard pot, and a teaspoon in hot water, swallowed, was credited with bringing relief to nasal congestion in coryza, sinusitis and the many allergies then called hay, rose, goldenrod or pollen fevers.

Mustard was always trusted, cheap and readily available all year in leaf, seed or ground form. It shows diversity not only of form and function, but also of color, from black or white in the plant to brown, tan or yellow in preparations.

If mustard held a family reunion picnic it would need an enormous park. Its kin, all members of the plant family brassicaceae, include cabbage, cauliflower, broccoli, turnips, radishes and watercress. All share in the family characteristics of strong flavor, zest and zip. They are a congenial tribe, supporting each other; these vegetables cooked with a few mustard seeds in the pot have increased authority.

Mustard is sharp and serene, equally at home on a ballpark hot dog, on deli sandwiches, at elegant buffets, on family tables or dinners for chiefs of state.

Pickling spices and curry powders contain mustard. In many areas of rural America, it is still valued as a spring tonic, a come-on for listless appetites, a purgative, and, in stronger solution, an emetic.

Methods of preparation differ widely. In the Orient and Great Britain, the ground seeds, mixed only with cold water, a fillip, sometimes jolting, to meats, fish and seafood. In France, table mustards are ground more coarsely and mixed with vinegar, salt and spices, to make a drier and grainier concoction than the smooth American brands. Dijon and other French mustards contain the ultimate Gallic blessing -- wine.

A word of warning: The very dark, grainy mustards can look much like pates on a buffet table. A bit spread on a toast triangle can cause instant and bug-eyed perception of one's error.

A teaspoon of mustard stirred into a non-dessert souffle can make bells, not alarms, ring in the dish. Boned roasts of lamb, pork and veal, with slivered garlic poked into the meat and then the whole coated with a thick blanket of grain mustard, much as a cake is frosted, are tender and piquant. The mustard is insulation; its flavor permeates the meat and juices are kept within.

The timelessness of belief in the power of mustard was recently reiterated in our newspapers. In Lansing, Mich., three women were convicted of indecent exposure and joyriding. Dressed only in thick slaverings of mustard and their shoes, witnesses said, they had climbed into a van and set out to be evangelists of the word of God. The defendants agreed that they had been seized by religious zeal, and left the court after conviction with no further word -- not even one for the brand of mustard, which I, for one, would like to know.

Perhaps it is as an ingredient of sauces that mustard shines most brightly today in our kitchens. From the simplest white sauce or veloute to the more complicated vinaigrettes or roast comforters, the addition of mustard, judiciously used, can add that special flavor we all look for now and then, when serving familiar and favorite foods. MUSTARD SAUCES AND DRESSINGS -- UNCOOKED MUSTARD VINAIGRETTE FOR MIXED GREEN SALAD MIMOSA 1 tablespoon wine vinegar 1/2 teaspoon salt 1/2 teaspoon finely ground black pepper 1tablespoon dijon mustard 2 tablespoons chopped parsley 1/4 teaspoon each chervil and tarragon Romaine, spinach, endive or green of your choice 1 hard-cooked egg

Mix wine vinegar with salt and black pepper. Add mustard.Blend with whisk. Add chopped parsley, chervil and tarragon. Pour over greens and toss thoroughly to coat all the leaves. Put hard-cooked egg through food mill and sprinkle on top. MUSTARD BUTTER FOR CANAPES FISH OR SEAFOOD SALADS 6 tablespoons soft butter 2 tablespoons good mustard

Mix softened butter with mustard and chill at least 15 minutes. CREAM MUSTARD DRESSING FOR CHICKEN, HAM, LAMB OR PORK, EGGS AND SALADS 1 cup heavy cream, plain or whipped 1/2 teaspoon lemon juice 1 teaspoon prepared mustard Dash salt and pepper

To heavy cream, add lemon juice, prepared mustard and salt and pepper. Mix well with fork. SWEET-SOUR MUSTARD SAUCE FOR ROASTS 1/2 cup catsup or bottled chili sauce 1 tablespoon dry mustard 1 tablespoon wine vinegar 1/2 teaspoon curry powder 2 tablespoons brown sugar softened in 1/4 cup red wine

Combine catsup or bottled chili sauce with dry mustard, wine vinegar, and curry powder. Blend well. Add brown sugar/wine mixture and blend again. Heat in double boiler if hot sauce is wanted. Mustard sauces -- cooked HOT MUSTARD BUTTER FOR BROILED, BAKED OR SAUTEED FISH 6 tablespoons butter 1 tablespoon boiling water 2 tablespoons dijon mustard

Melt butter in small saucepan, add boiling water and stir well. Stir in mustard. Heat briefly, stirring, and pour over cooked fish. HOT MUSTARD SAUCE FOR ROASTS, HAM, CORNED BEEF

This is particularly good on roast duckling. 2 whole eggs plus one yolk 1 tablespoon dry mustard 2 tablespoons tarragon or wine vinegar 1/4 cup olive oil 1/2 teaspoon each salt and pepper Paprika

In mixer at medium speed, beat whole eggs plus yolk. Add dry mustard, vinegar, olive oil, salt and pepper and sprinkling of paprika, beating constantly. Cook in top of double boiler, stirring, until thick. If thinner sauce is desired, thin with light cream to desired consistency. HOT VELVET SAUCE FOR SEAFOOD 2 tablespoons prepared smooth mustard 2 tablespoons flour Salt 1 teaspoon sugar 3/4 cup clam juice 2 tablespoons white wine 2 slightly beaten egg yolks

In the top of a double boiler blend mustard, flour, pinch of salt and sugar.

Stir in clam juice and white wine. Cook over hot water, stirring, until smooth and beginning to thicken. Remove from heat, add 2 slightly beaten egg yolks and cook over low flame, stirring, until thick.

This sauce is excellent over pasta, with the addition of 1 cup chopped clams, 1 crushed garlic clove, and 1 cup light cream added before the eggs. The last two sauces here are also very good with omelets, especially with diced ham or mushrooms added.