TEA IS the most important item on a Japanese menu. Meals begin and end with it. It is also the center of chanoyu, the ancient tea ceremony that some Japanese still perform wherever they are living. The tea ceremony is not an act of drinking tea; it is a way to devote oneself to an inner spiritual world, to ease he disruption caused by our busy lives.

The premise of chanoyu can be summarized in four Japanese words: wa, harmony among people and with nature; kei, respect, an expression of gratitude toward all things; sei, purity, the desireless freshness of heart; and jaku, tranquility of people and nature. Spiritually derived from Zen Buddhism, the tea ceremony helps the Japanese confront nature, enjoy peace and share friendship, forgetting the hectic outside world.

Tea was first introduced to Japan from China by Buddhist monks around 700 A.D. (The Chinese originally drank it with salt, giner or onions.) A Japanese legend, however, attributes the discovery of tea to the Indian monk Budhidharny, who stared at a blank wall in meditation for nine years before becoming a Buddha. Troubled by sleep during his long devotions, he cut off his eyelids and threw them on the ground. To his surprise, they took root and grew into tea bushes whose leaves made a drink that banished sleep.

Whether or not the legend is based on fact, caffein-rich tea was commonly drunk by Zen Buddhist monks to help keep them awake during their long meditations.

When the monks first brought tea to Japan, they would gather together in a plain, austere room and drink boiled, powdered, green tea out of a common bowl before the image of a Buddha. Any words said were uttered in low-pitched voices and the mood, although sociable, was primarily one of quiet devotion.

During the 15th and 16th centuries the tea ceremony evolved, becoming important to many Japanese, not just Buddhist monks. It was a refuge from the internal wars that tore the country apart during those years. Rulers appointed tea masters, and the ceremony was elevated to an art form, which it is still considered.

The tea ceremony itself is an exercise in self-discipline. The ceremony teaches the Japanese how to be good hosts and good guests; one learns the art of mutual consideration between the host and the guest. At one time, learning how to perform the ceremony was a prerequisite to marriage for a young woman. It currently takes about four years to become a tea master, or teishu, and a couple of yers to become an assistant, or hanto, who carries tea to the guests. Today, tea ceremonies are not that common in Japan.

To experience the ceremony first hand, I went to the Japanese Embassy where there is a traditional bamboo tea house behind the chancery in an outdoor courtyard garden. Before you enter, you remove your shoes and then bend to pass through the low doorway or "humble entrance."

Inside the tea house there is a small room on the left where the tea preparations are made, and a room to the right with a raised platform where the ceremonies are held. Rice mats cover the floor; the walls are sparsely decorated with art.

A woman dressed in a kimono beckoned me to come sit beside her. Without any verbal communication it was obvious that I must sit as the other four guests, with the balls of my feet not leaving the floor and my hands pressed lightly against the front of my thighs. It was not a very comfortable position.

In front of the women, the hostess prepared the tea. She bowed as I entered. The principal utensils used are the chawar, tea-bowl; chaire, tea caddy; chasen, bamboo tea whisk, and chasnaku, bamboo scoop. Each is a piece of art in itself, simple and elegant. There is also a brazier, kettle, water jar, ladle-stand, hibachi, waste-water receptacle and a lid rest.

Five soft strokes on a going signaled that the hostess was ready. Water was boiling on a charcoal fire in a box-like hole in the brazier. The hostess then placed some usucha, a thick, pasty, dark green tea made from the powdered young leaves of young plants, in an earthenware bowl. With the bamboo whisk she beat the water and the tea to a green froth. Poets have called this "froth of the liquid jade."

Meanwhile, guest number one received a sweet bean cake taken from a tray and placed on a piece of paper, called kaishi. She took the cake, admired it and bowing to the guest to her left, said "osaki-ni," or "before you," apologizing for eating first. She then took a few bites of the daintily colored cake and placed the remainder in the paper to take home.

Then the hostess placed the bowl of tea in front of the most honored guest -- chosen by the hostess -- who received it with ceremonial gestures, studied the beauty of the bowl, faced the design away from her, took three sips and drank all the tea. When she was finished, she wiped the bowl with a tissue and returned it to the hostess.

Once everyone had drunk the tea, the ladles and other utensils were admired by the guests, who asked questions about the various pieces. Then the fire was dimmed and the guests filed out. The entire ceremony took about 30 minutes. Throughout, there was a mood of tranquility.

Afterwards, the women, wives of Japanese diplomats, told me that they had learned the tea ceremony as adults because they wanted to preserve the tradition. Once began when she was at the university because she liked Japanese porcelain and pottery. Another became interested because the ceremonies gave her an opportunity to wear kimonos and to chat with friends.

This ceremony was informal. Others are far more formal and can last as long as four hours.

It changes somewhat with the seasons. From November to April a square fireplace, built in the floor of the tea house, is often used, or a brazier is used, as at the Japanese Embassy. From May to October, only a brazier is used, and it is moved close to the guests as the season gets colder. If the weather is good, the tea ceremony is held outdoors in the lovely Japanese gardens.

It is said that to understand and appreciate the beauty and discipline of the tea ceremony is to know the true Japan.