Clothing is far more than something to cover the body and protect a person against the elements, says Jean L. Druesedow, associate curator of the Costume Institute at the Metropolitan Museum of Art. Clothing provides a vivid and intimate glimpse into the past.

"I look at wearing apparel as a historical record," Druesedow explains. "Certainly, I love fashion for fashion's sake. But the cultural and social implications inherent in a style are much more fascinating. Silhouettes, fabrics and ornamentation are some of civilization's most important artifacts."Druesedow received degrees in speech and theater from Indiana University and joined the museum staff in 1978 (she took over her present position in 1984). In her job, she deals with over 40,000 "important artifacts" every day. That's how many garments make up the Costume Institute's impressive collection.

The collection had modest beginnings. It was founded in 1937 as the Museum of Costume Art by Irene Lewisohn, Aline Berstein and Polaire Weissmann and was built around outfits Lewisohn and her sister Alice Crowley had accumulated over the years.

The group first was housed in an area so tiny you couldn't even call it a suite. Later there was a move to Rockefeller Center, but that proved to be too expensive. Remarkably Polaire Weissman, who had become the executive director, hung on, staging benefits and seeking support from the design community. But meeting daily operating expenses wasn't easy. In spite of financial woes, the costume museum survived and its reputation grew. Finally, the idea was advanced for an association with the Metropolitan Museum of Art, and in December of 1944 the alliance was announced.

Today the institute covers 45,000 square feet on the ground floor of the Met and includes places to study (fashion students and Seventh Avenue designers frequent the institute), a reference library, a classroom and storage and restoration areas.

There also are impressive galleries where exhibitions regularly take place. Exhibitions in the past - most curated by the institute's special consultant Diana Vreeland - have focused on famous designers and famous eras in fashion. Many of the outfits that have been displayed have been loaned from other museums, fashion houses or private collections.

More recently, Druesedow and her staff decided to showcase the institute's own treasures. The display they mounted - "In Style: Celebrating 50 Years of the Costume Institute" - colorfully depicted three centuries of apparel design and paid homage to the founders of the costume museum who so resolutely pursued their dream.

Among the significant costumes on display was a striped wool gown embroidered with silver, dating from about 1695. The musuem's earliest complete European costume is considered by many authorities to be the finest example of its kind in existence in the United States. It was purchased by the institute from the Kimberley Collection and is typical of dresses worn by fashionable ladies of the era.

Back then, Druesedow notes, many dresses were made of two pieces - a robe pulled open and draped at the back to expose the richly ornamented petticoat beneath.

Moving into the 1700s, gowns with wide panniers (an elliptical hooped underskirt) moved to the forefront. These gowns allowed for little active movement but fit right into an era of elaborate court balls. Dresses featuring juxtapositions of lace motifs, ruched ribbon, flowers and fringe also were popular.

Men's clothes were adorned with richly decorative motifs and often a textile designer, weaver, embroiderer and assorted other craftsmen would be employed to turn out a suit. Banyans were significant menswear styles, too. The banyan is a robe-like, loose-fitting, informal costume that tends to be less constricting than most waistcoats and jackets.

As time went on, silhouettes and trims and materials became less complicated and ornate. People tired of elaborate attire that was so difficult to manage. Panniers disappeared. Two-piece dresses were considered demode. In their place appeared "round gowns" - simple one-piece styles. Striped silk coats for men were popular, but excessive beading wasn't as prevalent.

Simple muslin and lace became stylish in women's clothing, as an era of romance began to dawn.

By the 19th century, this romantic movement was in full swing. Ornamentation began to reappear but instead of extensive beading, trims often were simply mull puffs at the hem or neckline.

Around 1830, Druesedow says, the prevailing silhouette had made a transition from the columnar to the X-shape - wide at the shoulder and wide at the hem. Sleeves had grown steadily into the gigot or leg-of-mutton.

Hoops came on strong in the 1850s. The invention of the sewing machine in 1846 encouraged the easy application of braid or soutache to costumes. And many outfits of the day sport these touches.

By the 1870s, many smart women were wearing dresses that had bustles. The bustle wasn't a very practical touch, but other design elements were incorporated in women's clothing about the same time were. Some dresses had two bodices, for example - one for dressy occasions, the other for more informal times. Separate collars and cuffs also were often included because women were doing more traveling and needed such utilitarian items.

Bustles deflated at the end of the decade and the hourglass figure became the important fashion silhouette. By the turn of the century, an era of gracious elegance had dawned, full of laces and big hats and parasols.

The famous designer Paul Pioret soon came on the scene to steal fashion thunder from Charles Worth, who had established the first couture house in Paris in 1858. Pioret changed the entire course of fashion, streamlining the silhouette and going with the trend to somewhat shorter skirts.

Another significant 20th century designer: the great Coco Chanel, who realized that increased liberation for women would necessitate a different type of clothing. To meet these new challenges, she offered uncomplicated silhouettes, knits and walking suits - many styles that look as fashionable today as they did when they first appeared on the scene.

Still other important names : Madame Vionnet, known for her bias cut; Cristobal Balenciaga, known for his elegance; Dior, who introduced the "new look" in 1947; Elsa Schiapaerelli, noted for her imaginative, humorous work; Norman Norell, Adrian and Claire McCardell, who brought comfort, casualness and interesting textures to the forefront of fashion; and Charles James, who built beautiful clothes like architecture to fit our modern times.

The designers and historically significant clothes featured at the "50 Years of Style" exhibit comprise just one small portion of the Costume Institute's "closet." And the collection is growing every day through museum purchases, bequests and such.

What criteria are used to judge a new acquisition?

Aesthetic qualities are paramount, Druesedow stresses. The piece of apparel should represent the artist's best design techniques and should have some cultural significance. The condition of the garment, whether it can be preserved for the future, also is a determining factor.

"We're working now to improve our preservation methods," the assistant curator of the Costume Institute says. "Every item that is questionable is taken to our diagnostic center. There we photograph the damaged parts of the garment so we can study them and decide if something can be done to repair the problem. Ultrasonic techniques are being developed so that sound waves can be used in cleaning these old garments. They jiggle the dirt off in about three seconds without having to expose the fibers to detergents or water, which are so harmful to old and fragile textiles."

If the item can be saved, it is repaired by experts on the institute staff and then stored away in acid-free paper in an acid-free box in an atmosphere where light, temperature and humidity are all carefully controlled.

Precious costumes will be removed only for special museum projects, fashion research or for an exhibit. But even though the clothes are carefully guarded, Druesedow feels they must be accessible - after all, that's the role of the museum in the first place. And every effort is currently being made to computerize and better catalog inventory so it will be easier for fashion scholars and clothing designers to work with the collection.

Every effort also is being made to present interesting and educational costume exhibits.

It's no small thing to put an exhibit together, Druesedow emphasizes. It takes months of planning - three years to formulate and prepare a really big installation. There are people preparing the clothes and dressing mannequins for exhibits almost all the time.

During these summer months, the galleries are full of Asian costumes (that exhibit continues through Sept. 4). On Dec. 15, a Victorian costume presentation will open, complete with a gala benefit party (the Victorian exhibit goes until April 16).