So do you think of reading those kinds of books as a creative source in themselves, or is it just an activity that makes the creative process easier for you?
Why does it have to be an either or? I think that any activity where you can sort of shut down the analysis and planning centers of your brain while allowing room for free-association thoughts, subconscious wandering, mind-expansion, or whatever you wanna call "not acting like neurotic paranoid primate that evolution made your distant ancestors into." Like Marrow Machines said, "activate your brain." Trying to grasp astrophysics has given me a little bit of insight into light, which can translate in some ways towards what I know about sound - both are waves oscillating at specific frequencies that are perceived by our brains in subjective but generally similar ways. It makes me look at sound differently the next time I approach it, and in my opinion makes me more open to new ideas.
At the same time,
not thinking about music gives my mind some time to work through a lot of the issues I'm having
with music. Cleaning dishes by hand or folding laundry is another good example of that for me; I've had epiphanies about what to do with my tracks just because I gave myself the time away to be monotonous.
Sometimes I feel that you are either creative/musically inclined or you're not.. it's just like with the other thread about forcing yourself to produce.
There's no such thing as being "musically inclined" or "creatively inclined". You have drives and you have desires. If you desire something, you'll try to achieve it. If you have drive towards something, you'll do whatever it takes to achieve it, no matter how difficult that thing is to achieve. Everyone
desires to be creative, because artistic expression allows us to get out thoughts and emotions we cannot otherwise express. Not everyone has the
drive to be creative, because artistic expression is one of the easiest things to start and one of the hardest things to master. If you're not 100% passionate about it, there is no amount of desire that will give you that drive.