Claude Debussy

My wife, Neval, and I celebrated our sixth anniversary a few weeks ago and did something new: we went to the San Francisco Symphony. 

Garrick Ohlsson played Rachmaninoff's Third Piano Concerto, which we enjoyed. For the encore, however, Ohlsson announced the piece as something "that is so famous it needs no introduction" and went on to play a breathtakingly beautiful, elegant piece. 

We actually didn't recognize the piece, but @sfsymphony helped out:

And here it is: