How many times have you wished that you could freeze a moment of music in time, that you could savor it and revel in its delights at leisure? But of course you can't. The moment passes inexorably.

It passes inexorably, that is, except when Peter Serkin plays. In a performance of surpassing beauty at the Kennedy Center last night he seemed to defy time. Again and again, as the Beethoven "Diabelli" Variations unfolded their glories, he molded time to his own will. The music always moved at the most satisfying pace, but at the same time seemed to linger long enough for the closest scrutiny.

Serkin is a pianist who both listens to what he is doing and hears it accurately. His prodigious power of concentration is what gives him such control, and his extraordinary imagination makes what he has to say worth hearing.

This was a hard act to follow, and the three Chopin Nocturnes that did follow the Beethoven suffered in contrast but not in artistic terms.

The concluding Mozart Sonata K. 570, a piece as delicate and fragile as the Beethoven is monumental, received the same attention and flourished under it.

This was a truly memorable occasion in a musical season that, thus far this year, has been no slouch.