Castenda gives hints and clues toward and ancient philosophy. Specifically he deal's with "Petty Tyrants" - those who use their position and abilities to enslave or torment others - and teaches the reader the art of facing them without flinching.
It is thought, that if one can do this successfully, repeatedly, he can face anything the universe can throw at him. This is the subtle art of becoming Impeccable.
Also reccomended in the superhero 101 collection is Bouris Mouravieff's Gnosis I, Ouspensky's In Search of the Miraculous, and everything by Georges Gurdjieff.