In the age of Constantine the sign of the cross had come to be used by the primitive Christians in all their ecclesiastical rites, in all the daily occurrences of life, as an infallible preservative against every species of spiritual and temporal evil. A contemporary writer affirms with perfect confidence that in the night which preceded the last battle against Maxentius Constantine was admonished in a dream to inscribe the shields of his soldiers with the celestial sign of God, the sacred monogram of the name of Christ; that he executed the commands of Heaven; and that his valour and obedience were rewarded by the decisive victory of the Milvian Bridge. The senate and people, exulting in the success of Constantine, acknowledged that his victory surpassed the power of man. The triumphal arch which was erected about three years after the event recognised that by an instinct or impulse of the Divinity Constantine had saved and avenged the Roman Republic. Twenty-six years after the event the historian Eusebius narrates that in one of his marches Constantine saw a luminous cross in the sky inscribed with the words, "By this conquer," and this sign astonished the whole army; and that in a vision of the ensuing night Christ appeared to the Emperor, displaying the same celestial sign of the cross, and directing him to march with an assurance of victory. These incidents were universally adopted, as undoubted truths, by the Catholic Church both of the East and the West; but it is noted by the sceptics that, though the Fathers of the fourth and fifth centuries often celebrated the triumphs of Constantine, they do not allude to these signs and wonders as accompanying the event. THE EMPEROR CONSTANTINE PREACHING (A.D. 314).