The Cross is so common in Christianity that it is nowadays totally forgotten that it was not used by early Christians, since they had other symbols for the religion they wanted to establish. It took time for Christians to accept the cross as a symbol, as it was on it that Jesus died. It is as if the French revolutionionaries took guillotine to be a symbol of French revolution or a plane crash to symbolize the progress of the airplane industry.
One of those earliest symbols is Chrisme (Chrism). Chrisme is the monogram composed of the letters X (Chi) and P (Rho) and it predates Christianity. It is found both on amphorae to indicate their content and in pagan Greek and Egyptian manuscripts, as an abbreviation of the word χρηστός / khrēstós, which means “useful , auspicious”, indicating either a wish or an approving comment. Early Christian referred this word to Christ.
Chrisme can be found on countless amulets. It appears very often on paintings, Byzantine coins, medals, mosaics, stained glass windows and sculptures of Christian inspiration. It is sometimes inscribed in a circle, or a square. It was mainly present in the East, more specifically in the eastern part of the Roman Empire. According to Lactantius, the emperor Constantine received in a dream the message to mark the shields of his troops with the “celestial sign of God” the day before the battle of the Milvian bridge against his rival Maxentius at the gates of Rome in 312. Eusebius of Caesarea, hagiographer of Constantine, reports in his Ecclesiastical History that Constantine had the vision, shared by his soldiers, of a cross appearing in the sky and accompanied by the message: “In hoc signo vinces” (“By this sign you will conquer”). All in all, what Constantine might have seen in the sky would be more of form of a chrisme than of a cross.
Constantine had this sign transferred to his military ensign. A first appearance of Chrism appears on the emperor’s helmet on a coin minted in 315 in Ticinum to celebrate Constantine’s decennial anniversary. It appeared occasionally on a few occasions, used by Constantine as a victorious symbol, as well as on coins minted in 327 in Constantinople. The symbol was then adopted by Christianity and it served as the emblem of the Christian emperors who succeeded Constantine, but from the 5th century onwards it was gradually supplanted by the cross.
Chrisme had different forms. The Simple Chrism is composed of the two Greek letters Ι (Iota) and Χ (Chi) for the initials of Ἰησοῦς Χριστός (Jesus Christ). Another form has the appearance of a six-pointed star often identified in art with the star that guided the Magi. The Constantinian Chrism, the most widespread, is composed of the two Greek letters Χ (Chi) and Ρ (Rho), the first two letters of the word Χριστός (Christ). Finally, there is a cross variant, consisting of the Ρ (rho) crossed by a horizontal line. It is also often accompanied by the letters α (alpha) and ω (omega). These letters, which frame the Greek alphabet, symbolize totality: the beginning and the end.
