Four books have helped me in this regard. First, The Encyclopedia of Symbols, a reference book which I consult in the library but is not available for checkout. Secondly, Man and His Symbols, by Carl Jung. This is the definitive book on the subject. Also, Crouching Tiger, Hidden Dragon: Portrait of a Film discusses the symbolism of that movie (some of which was used in BBM as well) and also has an introduction by Ang Lee discussing his spiritual beliefs. Finally, Chinese Mythology by Anthony Christie is also illuminating. I also have a small handbook on Chinese Symbolism which I carried in my purse on trips to the theater to see BBM!