At a piano festival like the one that accompanied the just-completed William Kapell Competition of the University of Maryland, at which you have seven distinguished pianists playing seven nights in a row, programming poses all kinds of problems. Repetition is one. Bach's "Goldberg Variations," for example, are wonderful, but seven nights in a row? Another problem is how to prevent the offerings of those players who come last in the series from sounding like afterthoughts.

The man who came last, on Friday night, was the renowned Beethoven authority Anton Kuerti. He solved the programming problem decisively by offering a mighty portion of very late, and very great, Beethoven. There were the seldom-played Six Bagatelles, Op. 126, followed by the last three of the 32 sonatas If there is an Everest of piano music, these three sonatas are probably it.

This is music of extremes, meant to test the expressive limits of music as Beethoven conceived it. The sonatas -- and the bagatelles, too -- are often harsh, both in sound and in expressive intensity. Harmonically they are harsh too, more dissonant than music had ever been before. Construction of phrases is bare-bones. Beethoven has cut out as much of conventional decoration as could be done. Phrases do not follow formulas; they are convoluted with extreme augmentation and diminution of the material. The phrases often lie at the top and bottom ranges of the keyboard, on occasion at the same time.

Kuerti's playing, in many ways, shares the characteristics of the music -- craggy, intensely intellectual and raptly committed. He was invariably at his finest where the music was most difficult. He seemed to lie in wait for those movements and then apply a mental power that brought the high spiritual drama of these sections to life in an almost sacramental manner.

The movements in point are the final ones of each sonata. In the 30th sonata, Op. 109, it is a set of variations deeply imbued with a sort of metaphysical obeisance. In the 31st, Op. 110, it is a mighty fugue. And in the last one, it is an intensely dramatic series of variations that is the most philosophic of all, building to a hushed final affirmation that is secular religion if I ever heard it.

With Kuerti, the tenderness and the suffering were equally eloquent. And in those moments where Beethoven has stretched the phrases so far that they barely can breathe at all, Kuerti was very fine.

Most impressive, though, was the way he kept the fundamentals of the successive variations in such precise focus with each other, greatly enhancing the cumulative impact. It was a remarkable feat of concentration.