WHAT ARE the four treasures of the scholar's study? Paper, a brush, an ink stick and an ink stone, according to "Painting and Calligraphy of the Ching Dynasty," at the Freer Gallery. When the ink stick is ground with water on the hard surface of the ink stone, the scholar can begin to write.

In this exhibit, 30 masterpieces show some of the evolution of Chinese painting and calligraphy from the 17th through the 19th centuries.

With "A Visit in the Rain to Painter Tai," Shih-tao stands out among a group of painters known as the individualists. This hanging scroll has been on display before at the Freer in recent memory, but its "wet look" is always refreshing.

There are handscrolls as well, unrolled for our viewing, though not exactly as the artists intended. Paintings of landscapes, the handscrolls were meant for one or two connoisseurs to slowly unfurl and hold open to a partial scene. Calligraphy on the margins further illuminates the paintings.

With calligraphy writ large, hanging scrolls by master calligraphers demonstrate the many possible faces of Chinese letters -- bold or dainty, plain or ornate. Translated, an 18th- century poem written in calligraphy needs no illustration when it tells of "moonlight of jade flutes and plum blossoms."

The "scholar's treasures" on display here belonged to one scholar in particular, Charles Lang Freer. The set of writing instruments was given him in 1918 by Pang Yuan-chi, a Chinese art collector from whom, not incidentally, Freer also acquired many important paintings.