Creativity
"If you scratch any interesting artist you’ll hear that one of the key components to how they do it is that they don’t really know what they’re doing."
Paul McCartney recording drums in a bathroom for McCartney II, 1980. Image via The McCartney Project. 
Paul McCartney has long insisted that he doesn’t really know where the music comes from. He didn't learn to read or write music, afraid that to do so would interrupt or break the way he works. He also places great emphasis on starting and finishing work immediately, before you have had the chance to overanalyze or come up with an excuse not to do it. 

Article: McCartney on Not-Knowing and Doing it Now