THE WEEK'S OTHER MIRACLE WAS, OF COURSE, Thomas Quasthoff's half-program with the Chamber Orchestra: Bach's "Ich habe genug" Cantata and four Mozart arias. The shock in the sight of Quasthoff onstage, his body the victim of Thalidomide, lasts perhaps half a minute; you marvel at his agility, his infectious huge smile, the utter absence of self-consciousness with which he has conducted his career. Then you listen, to that big voice so smooth, so flexible in the service of music's moods, so utterly pure in its dark beauty. You think: This is the voice for Die Winterreise, and there's already an RCA recording to prove you're right. The fogies among us spent the intermission riffling through memories of Hans Hotter, Paul Schoeffler, George London, Dietrich Fischer-Dieskau, of course, and Hermann Prey. The circumstances around Quasthoff make comparisons difficult, but one impression stands out: In a world where outrageous premiums are placed on differentness -- or have we already forgotten David Helfgott? Andrea Bocelli? -- Quasthoff comes to us to make music, and he does it right now as well as anyone on the planet.