In Hoc Signo Vinces - History

History

The historian Eusebius states that Constantine was marching with his army (Eusebius does not specify the actual location of the event, but it is clearly not in the camp at Rome), when he looked up to the sun and saw a cross of light above it, and with it the Greek words "εν τούτῳ νίκα" ("In this, conquer"), often rendered in Latin as In hoc signo vinces "in this sign, you will conquer"). At first, Constantine did not know the meaning of the apparition, but on the following night, he had a dream in which Christ explained to him that he should use the sign of the cross against his enemies. Eusebius then continues to describe the Labarum, the military standard used by Constantine in his later wars against Licinius, showing the Chi-Rho sign.

The phrase appears prominently placed as a motto on a ribbon unfurled with a passion cross to its left, beneath a window over the Scala Regia, adjacent to the equestrian statue of Emperor Constantine, in the Vatican. Emperors and other monarchs, having paid respects to the Pope, descended the Scala Regia, and would observe the light shining down through the window, with the motto, reminiscent of Constantine's vision, and be reminded to follow the Cross. They would thence turn right into the atrium of St. Peter's Basilica, ostensibly so inspired.