Last night's National Symphony concert began and ended like the one on Thursday, with Reger and Stravinsky. What happened in between -- and will be repeated tonight -- made this pair of concerts unique. Jessye Norman, who was available for only two of the orchestra's concerts, sang the Four Last Songs of Richard Strauss, and what had been merely an excellent program became a transcendent experience.

The Four Last Songs were not quite the final work of the composer's long career; a later, unpublished song was discovered not long ago. But they still are a kind of valediction, and they embody uniquely the distinctive blending of orchestral sounds with the human voice that is Strauss' hallmark. They would make him a great composer even if he had not written "Till Eulenspiegel," "Don Quixote" and "Der Rosenkavalier."

This music, written for Kirsten Flagstad, ideally requires her unique combination of power, rich tone, expressive depth and flexibility -- a voice that can blend with and dominate an opulent orchestra. Norman's is one of the few such voices that have appeared since Flagstad left the scene, and she made the music completely her own.

The beginning was glorious, even with the fairly prominent vibrato in the first song, but the singing improved steadily as the music proceeded. By the third song, "Beim Schlafengehen" ("Going to Sleep"), it was awesome -- totally smooth and seamless throughout its range, used with apparently effortless ease and sensitive to the subtlest expressive nuances. Rafael Fru hbeck de Burgos conducted with a polish and involvement comparable to the singer's, and the playing was exalted, notably in the important violin and horn obbligatos.

Should the NSO offer such an event to half of its subscribers and not to the others? The question must be asked -- but surely it was better to have it happen for two evenings than not at all.