I remembered a story of how Bach was approached by a young admirer one day and asked, "But Papa Bach, how do you manage to think of all these new tunes?"  "My dear fellow," Bach is said to have answered, according to my version, "I have no need to think of them.  I have the greatest difficulty not to step on them when I get out of bed in the morning and start moving around my room."  ~Laurens Van der PostFD