Lion in winter. Concert audiences now whoop and whistle for their artists, and I couldn't help but wonder how this affects Maurizio Pollini. At sixty-nine, he has been before the public for fifty years, ever since winning the Chopin International Competition in 1960 at the age of eighteen. His white hair is wispy on top (this is art, so let's call it an aureole). He still walks briskly to the piano and hits the first keys with unnerving alacrity. When Rosa Ponselle made her London debut, the veteran diva Nellie Melba gave her a friendly warning: nothing but nothing could induce British audiences to give a standing ovation. Dame Nellie was reportedly quite put out when her young American rival earned a standing ovation at Covent Garden every night. Pollini earns the same, even when he ends his program, as he did last night, with Boulez's fearsome Piano Sonata no. 2. One way to insure that posterity will consider you a fool is to mock modern music, but in the annals of unapproachable and uningratiating works, the Boulez sonata must attain a kind of summa.