Yesterday my two young four-hand-duo students were struggling over a bar in Schumann's Trauer: a disaster, every time.

What happens in that bar? There is an F#, then an A-flat, and a B-natural. (The piece is in F major.)

I asked them to consider an analogy to such mucking about with the very tones that establish the identity of the key. One suggested it was like having lung surgery.

I'm not sure I would have chosen such an extreme comparison, but he was identifying change to the vital core of the key. For a person with a sensitive ear that would be like walking on a fault line--surely not a pleasant experience.

The question arises whether this young man's ear is too sensitive. I reply with another question: Was Schumann's ear too sensitive?