"Leaving out the accompanying moral code, which is in all cases a supplementary growth, a religious creed is definable as a theory of original causation.... [E]ven that which is commonly regarded as the negation of all Religion — even positive Atheism, comes within the definition; for it, too, in asserting the self-existence of Space, Matter, and Motion, which it regards as adequate causes of every appearance, propounds an à priori theory from which it holds the facts to be deducible."