If beauty is the beginning of terror, pianist Mitsuko Uchida brought her Kennedy Center Concert Hall audience Wednesday to the precipice of fear.

In works by Mozart, Schubert, Chopin and Webern, her playing made one understand exactly how lonely it must have been for these composers to write the music they did. In each work, played as if every note hung in the balance, that sense of artistic and expressive isolation became almost, well, terrifying.

Each of the four works on the program presented by the Washington Performing Arts Society was radical, and Uchida is radical for having grouped them together into a recital that looked innocuous on the surface but was very thorny on hearing.

Uchida isn't usually thought of as a radical player. For years she was considered primarily a Mozart pianist--perhaps the finest one of her generation. Then she became known for her Chopin and Schubert, again composers that suggest the pianist is likely a traditionalist. And the inadequate adjectives that cling to an artist like critical barnacles are all about the "delicate" nature of her playing--an adequate description of her keyboard touch, which is light and refined to the extreme.

Uchida is anything but a typical Mozart or Schubert pianist. The Mozart she chose for Wednesday's program is one of the composer's most mysterious, most anguished and most bizarre works: the three-page Adagio, K. 540.

It is almost never played and was written a few years before his death. It could have been an aria from one of his great operas: There are moments of exquisitely simple vocal singing, punctuated by stark orchestral statements, the kind of noise an opera orchestra makes to tell us that the character has come to yet another resolution, or a new doubt.

This is not how Uchida played it. Instead, she elongated the work to an astonishing extent. The tempo was barely a crawl, but her control of pianissimo playing was so powerful that the music survived, rendered into something transparent and tender, but strong as a sheet of Mylar.

Uchida played the Mozart immediately after Webern's Variations, Op. 27, seven minutes of snow falling on white paper. She didn't even rise from the bench during the pause between the Mozart and Webern. The two are of a piece, she suggested. And played with her characteristic faintness--the way that watercolors are faint.

Two sonatas, Chopin's B Minor and Schubert's colossal D Major, formed the bulk of the program. The Schubert was more successful than the Chopin.

Chopin's B Minor Sonata is a study in repression and unwanted release. Its last movement is a kind of tornado from the unconscious, and throughout the four-movement work there are harrowing examples of infantile emotion escaping from the well-trained adult mind (including the infinitely sweet middle section of the third-movement Funeral March). Uchida captured the rare, strange cries of quiet need.

The explosions, the times when months of managed grief yield to the adolescent demand for something that is lost forever, were less successful. More tone, more richness of sound, more sculpted fortes were needed.

Uchida's Schubert approached perfection. It is a sonata woven of thoughts that seem at first improvised, but become more and more palpable as the fundamental building blocks of the work.

Uchida let them emerge into their proper solidity and weight, bringing the listener to the sonata's increasingly wide vistas with the resolution of a tireless mountain climber.