THE GENTLE HILLS between Tokyo and Kyoto have long been a source of fine white clay for the Japanese pottery centers of Seto and Mino. The hills themselves nourished the industry, having just the right contours for many-chambered "climbing" kilns.

This kiln changed the potter's art, as can be seen at the Freer in the 41 delicate pots in "The Glazed Ceramic Tradition of Seto and Mino Wares."

According to show organizer Louise Cort, tradition has it that this tiered kiln was introduced to Japan through the Japanese campaigns in Korea in the 1590s. The military leaders brought Korean potters back with them; they were treasures, and so were their kilns.

When the potter Kagenobu heard about a special kiln built by Koreans, he went west to Karatsu to see for himself. The kiln was built within the walls of the local warlord's property, and so was off-limits; he returned to Mino unsatisfied.

Later, he realized the residence would be open to all on New Year's Day, as was the custom. He dressed in finery for the occasion, and paid his respects. When no one was watching, he went out for a close look at the kiln. He was the first to build such a kiln in Mino.

The Seto and Mino kilns were the first in Japan to produce glazed wares, and, says Cort, "They maintained that aura of having been the first and the best." They're still two of the biggest ceramics producing centers in Japan.

This is a show especially for potters, who will recognize the yellowish or greenish tint of wood ash glaze, the brown of iron glaze, and the thick, milky white "Shino" glaze from feldspar in ash glaze, a particular favorite nowadays. Potters can appreciate how the higher temperatures of the "great kiln," as opposed to the single-chambered tunnel previously used, made some glazes transparent and others merely lustrous. And introduced mass production.

From tea bowls to sake jars, the glazed ceramics in this show date from the early 14th to the 19th century. Postwar archaeological digs have helped to pin down some of these objects to within five years.

"It's through understanding that 16th- century kiln that potters are able to build a kiln of similar construction and approximate a Shino glaze," says Cort. "So archaeology has contributed to a 20th-century revival."

THE GLAZED CERAMIC TRADITION OF SETO AND MINO WARES -- At the Freer Gallery through November 17.