The idea of Mozart as some kind of savant -- a man-child who never outgrew the effects of his outlandish early life -- is trivial and insulting.

Still, writing music came easily to him, to an extent that he himself didn't seem to entirely understand. "I compose as a sow piddles," he once wrote with characteristic humor. (Compare this with Tchaikovsky's wonderfully disciplined account of the creative process: "I am at my desk at 9 o'clock every morning, and my muse has learned to be prompt.")

And his music is just as magical as his mind. Analysts armed with sophisticated explanatory tools can make the works of Bach and Beethoven, Wagner and Stravinsky yield up their secrets while Mozart's sorcery remains elusive.

There is something about all of this that is both marvelous and maddening, and it reduces even determined rationalists to gibbering about miracles. In the face of a great performance of "The Marriage of Figaro" or the G-Minor String Quintet, the famous line from Peter Shaffer's "Amadeus" about Mozart "taking dictation from God" can sometimes have the ring of truth.