On a visit to the Beethoven museum in Bonn, a young American student became fascinated by the piano on which Beethoven had composed some of his greatest works.  She asked the museum guard if she might play a few bars on it.  To help persuade the guard, she also slipped him a lavish tip.  The guard agreed and the girl went to the piano and tinkled out the opening of the Moonlight Sonata. 

As she was leaving she said to the guard, "I suppose all the great pianists who come here want to play on that piano."

The guard shook his head and said, "Paderewski was here a few years ago, and he said he wasn't worthy to touch it."