321, apparently at Rome, speaks of an army of divine warriors and a divine assistance which Constantine received in the engagement with Maxentius; but he converts it to the service of heathenism by recurring to old prodigies, such as the appearance of Castor and Pollux. This famous tradition may be explained either as a real miracle implying a personal appearance of Christ, or as a pious fraud, or as a natural phenomenon in the clouds and an optical illusion, or finally as a prophetic dream. The propriety of a miracle, parallel to the signs in heaven which preceded the destruction of Jerusalem, might be justified by the significance of the victory as marking a great epoch in history, namely, the downfall of paganism and the establishment of Christianity in the empire. But even if we waive the purely critical objections to the Eusebian narrative, the assumed connection, in this case, of the gentle Prince of peace with the god of battle, and the subserviency of the sacred symbol of redemption to military ambition, is repugnant to the genius of the gospel and to sound Christian feeling, unless we stretch the theory of divine accommodation to the spirit of the age and the passions and interests of individuals beyond the ordinary limits. We should suppose, moreover, that Christ, if he had really appeared to Constantine either in person (according to Eusebius) or through angels (as Rufinus and Sozomen modify it), would have exhorted him to repent and be baptized rather than to construct a military ensign for a bloody battle. In no case can we ascribe to this occurrence, with Eusebius, Theodoret, and older writers, the character of a sudden and genuine conversion, as to Paul's vision of Christ on the way to Damascus; for, on the one hand, Constantine was never hostile to Christianity, but most probably friendly to it from his early youth, according to the example of his father, and, on the other, he put off his baptism quite five and twenty years, almost to the hour of his death. The opposite hypothesis of a mere military stratagem or intentional fraud is still more objectionable, and would compel us either to impute to the first Christian emperor, at a venerable age, the double crime of falsehood and perjury, or, if Eusebius invented the story, to deny to the 'father of church history' all claim to credibility and common respectability. Besides, it should be remembered that the older testimony of Lactantius, or whoever was the author of the work on the Deaths of Persecutors, is quite independent of that of Eusebius, and derives additional force from the vague heathen rumors of the time. Finally the _Hoc vince_, which has passed into proverbial significance as a most appropriate motto of the invincible religion of the cross, is too good to be traced to sheer falsehood. Some actual fact, therefore, must be supposed to underlie the tradition, and the question only is this, whether it was an external, viable phenomenon or an internal experience.