By Fred Kirshnit
New York Sun

On Monday evening at the Walter Reade Theater, pianist Jeremy Denk performed a work of contemporary music so cutting edge, so revolutionary, that it shook the audience to its very core. Was it the latest dispatch from Finland? A piece where he had to play the keyboard with his elbows and stand up to pluck the strings of the inner sound board while playing a kazoo? No, it was the Waldstein Sonata of Beethoven ... He hears this percussive opening as more gentle than most. His ability to navigate these treacherous waters was commanding and reassuring. When he emphasized the timbral contrasts at both ends of the keyboard, he did so with remarkable precision.

Beethoven composed an entire slow movement, later published as the stand-alone Andante favori, but jettisoned it at the last moment, deciding that it was simply too conventional for his innovative brainchild. In its stead, he placed some measured chords that transition to the incredible Rondo that opens the finale. When this last movement began, Mr. Denk did something so radical that he may be in danger of being kicked out of the pianist's union: He read the score.

Virtually no practitioner actually follows Beethoven's instructions to depress the sustaining pedal and keep it down for an inordinately long time. If one did as the composer wished, the result would be a jarringly dissonant mixture of overtones that predates Debussy by 90 years. But Mr. Denk has discovered that old Ludwig was right after all. Having heard hundreds of Waldsteins over the years, I found this section truly refreshing; it made a strong case for the work's continuing contemporaneity.

Vladimir Horowitz developed a technical trick that made it seem he was performing with three hands by playing a distinct passage with his thumbs while intoning others in the right and left hand digits. I have no first-hand knowledge of the inspiration for this feat — he employed it most effectively in pieces by Rachmaninoff — but it may very well have been suggested by the ending of the Waldstein, where the left thumb must execute a trill for many measures while the rest of the hand journeys through some rather complex material. Mr. Denk handled these acrobatics flawlessly and built a powerful, lasting crescendo of the main theme, which culminated in a Prestissimo finish and a nuclear fission of thematic material — the individual melodies are reduced to three and then only two notes — with substantial excitement.