For anyone that knows classical western theory and finds it comes up
lacking. I highly recommend "George Russell - Lydian Chromatic Concept
of Tonal Organisation".
http://www.georgerussell.com/
George worked with Miles and friends, he's managed to build up a very
descriptive theory of how this new modern jazz thinking works.
In it's basics it's quite different, you use "Tonal Levels of Gravity" which
are based on 5ths. Each level introduces new color tones and takes you
further away from your base level of gravity. You can then use these
levels quickly in your playing to introduce "outside" sounds while having a
clear way to look at where you're getting these tones from.
The book is written like a technical theory, each sentence and paragraph
is quite clear and even the hardest concepts are clearly defined and just
take a bit of looking over. Very concise writting, contains all the reasons,
all the info.
This isn't for beginners. Although you'd do well to skip traditional theory
and go straight to Lydian theory, this is a bit impractical as you'd need a
teacher that's well versed in Lydian theory to do it properly. However if
you already know normal theory then Lydian theory opens a lot of doors.
-Ben