To put it rather bluntly, normal people do not compose – or they compose like Carl Czerny or Murzio Clementi. You need a certain amount of openness and non-conformism to be creative. People who are considered mad have not been taught by life to wall up their openness and they have more direct contact to their unconscious.

-Heinz Holliger

You can read that, and a whole lot more, here. It appears Mr. Holliger really loves Schumann.