Nobody steals books but your friends.
I have a fondness for technology. It's great to spend hours puttering around with mechanical things gotten from junkyards and visualizing what their use might be. Especially if you come across a gadget or tool and you don't know what it is and you try to figure it out. I'm fascinated by processes, whatever they might be.
I read Herman Hesse's 'Siddhartha' while I was writing 'Lord of Light' along with many other things. It seemed a good time to read it so I could see what he had to say about Buddha. In my first chapter, I was thinking in terms of the big battle scene in the 'Mahabarata.' It helped me in visualizing the battle in my novel.
The first time I met Harlan Ellison, we were both unpublished young punks in Cleveland, Ohio.
In a sense, fantasy is a freer play of the imagination. You can achieve exactly the situation you want with less groundwork, less of a need to fill in all of the background. For science fiction, I would use a lot of sources to set up, for instance, what a being from another planet would be like.
I do admire great essayists. I'm a particular fan of good nature writing. People like Robert Finch. I read great quantities of writing by naturalists. I've been studying the genre for years.