in michael moores book, 'playing in thumb pos.' he says that the harmonic minor is used to play over a minor 2-5-1. but everyone else here and elsewhere says that the melodic minor is more important and becuase marc levin wrote that the harmonic minor shouldnt be used to play over all the 2-5-1 (only parts of the scale) i think some people think this must be gospel. I think maybe the harmonic minor is better suited to the upright becuase you can stay in one key ,it's especially difficult to keep changing key in thumb position. so maybe different scales work better on different instruments? id rather take michales moores advice than marc levin's.