The obvious insufficiency however of this analysis to afford an entire explanation of the prejudices of these early unbelievers points to the close union before noticed(247)of the emotional with the intellectual causes. While asserting the possibility of the independent action of the intellectual element under peculiar circumstances as a cause of doubt, and while thus vindicating the importance of investigating the history of free thought from the intellectual side, we admitted the necessity of taking the probability of the action of the moral element into account when we pass from the abstract study of tendencies to form a judgment on concrete instances. Here accordingly, in the mental history of these early unbelievers, we already encounter cases where philosophy as well as piety requires that a very large share in the final product be referred to the influence of emotional causes. Christianity addresses itself to the compound human nature, to the intellect and heart conjoined. Accordingly the excitement of certain forms of moral sensibility is as much presupposed in religion as the sense of colour in beholding a landscape. The means fail for estimating with historic certainty the particular emotional causes which operated in the instances now under consideration. The moral chasm which separates us from heathens is so great that we can hardly realize their feelings. If however we cannot pronounce on the positive presence of moral causes which produced their disbelief, we may conjecture negatively the nature of those, the absence of which precluded the possibility of faith. Christianity demands a belief in the supernatural, and a serious spirit in the investigation of religion, both of which were wholly lacking in Lucian. It requires a deep consciousness of guilt and of the personality of God, which were wanting in Celsus. It exacts a more delicate moral taste to appreciate the divine ideal of Christ’s character than Hierocles manifested. Porphyry and Julian are more difficult cases for moral analysis. Porphyry is so earnest a character, so spiritual in his tastes,(248) that we wonder why he was not a Christian; and except by the reference of his conduct to general causes, such as philosophical pride, we cannot understand his motives without a more intimate knowledge than is now obtainable of his personal history. The difficulty of understanding Julian’s character arises from its very complexity. Who can divine the many motives which must have combined with intellectual causes at successive moments of his life, to change the Christian student, into the apostate, to convert disbelief into hatred, and to degrade the philosopher into the persecutor? History happily offers so few parallels to enable us to form a conjecture on the answer, that we may be content to leave the problem unsolved.