We possess a large treatise of Origen against Celsus; passages, directed against Porphyry, of Eusebius, Jerome, and Augustin; a tract of Eusebius against Hierocles; and a work of Cyril of Alexandria against Julian. Yet it is never perfectly satisfactory to be obliged to read an opinion through the statement of an opponent of it. The history of philosophical controversy shows that intellectual causes, such as the natural tendency to answer an argument on principles that its author would not concede, to reply to conclusions instead of premises, or to impute the corollaries which are supposed to be deducible from an opinion, may lead to unintentional misrepresentation of a doctrine refuted, even where no moral causes such as bias or sarcasm contribute to the result. Aristotle’s well-known criticism of Plato’s theory of archetypes is a pertinent illustration.(125) The slight difficulty thus encountered, in extracting the real opinions of the early unbelievers out of the replies of their Christian opponents, may for the most part be avoided by first realising the state of belief which existed in reference to the heathen religion, which for our present purpose may be treated as homogeneous throughout the whole Roman world. We shall thus be enabled as it were to foresee the line of opinion which would be likely to be adopted in reference to a new religion coming with the claims and character of Christianity. This prefatory inquiry will also coincide with our general purpose of analysing the influence of intellectual causes in the production of unbelief. Four separate tendencies may be distinguished among heathens in the early centuries in reference to religion:(126) viz. the tendency, (1) to absolute unbelief, (2) to a bigoted attachment to a national creed, (3) to a philosophical, and (4) a mystical theory of religion.