Being in the mood for slow simple-sounding yet soul-satisfying music, I turned to Mozart. The slow movement of his Concerto for flute and harp hit the spot. What to follow? I chose the first movement his Piano Sonata in A major – a piece that I have enjoyed playing since childhood, with it beautiful siciliene-like lilting theme.

Enjoying it, I suddenly noticed that it was in A major! A surprise? Yes. By now I expect A major pieces to start in B flat major, the key one semitone up. Or at least quickly shift up into that key. I listened carefully in anticipation of such a shift. I did not happen. Why? Other A major pieces as ingrained in my nervous system as this Mozart have shifted. Perhaps the simplicity of the theme, and its variations imprinted themselves deeper than their A major peers. How nice!