I can't vouch for or comment on the quality of any of his other writings, but the posted excerpt shows someone seriously ready for a change in medication. He actually managed to bring into his paranoia -- all at one shot -- the Greeks, evolution, the occult, mysticism, the Garden of Eden fable, Hinduism, witchcraft and reincarnation.
I've never seen that done before, and it really tastes of the "they're all out go get me" syndrome.