The hypothesis of a natural formation of the clouds, which Constantine by an optical illusion mistook for a supernatural sign of the cross, besides smacking of the exploded rationalistic explanation of the New Testament miracles, and deriving an important event from a mere accident, leaves the figure of Christ and the Greek or Latin inscription, '_By this sign thou shalt conquer!_' altogether unexplained. We are shut up, therefore, to the theory of a dream or vision, and an experience within the mind of Constantine. This is supported by the oldest testimony of Lactantius, as well as by the report of Rufinus and Sozomen, and we do not hesitate to regard the Eusebian cross in the skies as originally a part of the dream, which only subsequently assumed the character of an outward objective apparition, either in the imagination of Constantine or by a mistake of the memory of the historian, but in either case without intentional fraud. That the vision was traced to supernatural origin, especially after the happy success, is quite natural and in perfect keeping with the prevailing ideas of the age. Tertullian and other ante-Nicene and Nicene fathers attributed many conversions to nocturnal dreams and visions. Constantine and his friends referred the most important facts of his life, as the knowledge of the approach of hostile armies, the discovery of the holy sepulchre, the founding of Constantinople, to divine revelation through visions and dreams. Nor are we disposed in the least to deny the connection of the vision of the cross with the agency of Divine Providence, which controlled this remarkable turning point of history. We may go farther and admit a special providence, or what the old divines call a _providentia specialissima_; but this does not necessarily imply a violation of the order of nature or an actual miracle in the shape of an objective personal appearance of the Saviour. We may refer to a somewhat similar, though far less important, vision in the life of the pious English Colonel James Gardiner. The Bible itself sanctions the general theory of providential or prophetic dreams and nocturnal visions through which divine revelations and admonitions are communicated to men.