I'm trying to figure out the rules of chord progressions, how to build them, why some sound better than others, etc. and I was looking at getting Mark Levine's Jazz Theory Book to help me out. I want to have a good grounding in the theory to speed up composition - I'm tired of just banging out chords until something sounds "neat". I'd rather like to pick a key centre and narrow down my choices, and understand why some changes would work better than others. Then I can try breaking the rules after I understand the basics, right? Of course building lines over these changes is something I have to learn as welll. Then I saw at the store books by Mark Sarnecki called Harmony Book 1 and 2, and a book by Grace Vandendool called Basics of Harmony. They look to be over my head, as far as my theory sophistication goes at this point. But would I find more use from one of these Harmony books than Mark's book? Or should I just work through my favorite songs and try to discover it all on my own? This seems a little counterintuitive to me - why struggle slowly through a process that many others (much more talented than I) have gone through and codified?