Beethoven's "Hammerklavier" is the most vastly conceived, far-flung sonata he, or probably anyone else, ever created for piano. On any program on which it appears, it is inevitably the dominant work, as in Daniel Barenboim's brilliant account last night at the Kennedy Center.

The emotional and metaphysical dimensions are as immense as the physical scale, which took about an hour in Barenboim's very broad, deeply felt account. The immense slow movement especially was played very much in the Furtwa nglerian style that Barenboim also favors when he conducts the Beethoven symphonies. His ability to sustain those long, harmonically and rhythmically ambivalent lines was quite breathtaking. This great movement, with its profound pathos, is as moving for what it leaves unsaid as for what it says. But a straight, simple account would not make this clear, and would not reach beyond the surface to what the music is all about. Playing very quietly as well as very slowly much of the time, Barenboim penetrated the music's inner mystery.

And the concluding fugue that follows was ablaze with Beethoven's staggering intricacies and merciless twists of the performer's fingers.

In the two opening movements, Barenboim found more lyricism than is heard in the monumental accounts by Rudolf Serkin.

It was an all-Beethoven program, growing from the eight-concert survey of all 32 sonatas that Barenboim will begin tomorrow in New York.

For contrast with the exalted rhetoric of the "Hammerklavier," No. 29, Op. 106, Barenboim preceded it with one of the most bewitching of the sonatas, the one in E-flat major, Op. 31, No. 3. He performed this fanciful, playful work with enormous grace. The scherzo had such charm that some of the listeners in the full house interrupted with applause when it was over.

The opener was the Sonata in F-minor, Op. 2, No. 1, an early, lesser work -- beautifully played, however.

Throughout the evening, the playing had clarity and lovely tone.

Barenboim, by the way, has recorded all 32 sonatas on compact discs -- in two sets.

One final thought: It would be fascinating to hear what Barenboim the conductor would do with the noted orchestration of the Hammerklavier by Felix