Since on the 21st December the sun reaches its lowest point, and then begins once more to rise higher in the heavens, man, in his simplicity, marked the day on which this change in the sun became perceptible as the new birth or birth-day of the sun, the invincible Sun-God. What was more natural for the Christians of that age than to connect this obvious natural event with the thought of the nativity of Him who is the Light of the World! Even if the Holy Scriptures had not suggested this idea, it must have presented itself to the Christian mind. The comparison of Christ with the sun, and of His work with the victory of light over darkness, frequently appears in the writings of the Fathers. St Cyprian[332] spoke of Christ as the true sun (_sol verus_). St Ambrose[333] says precisely, “He is our new sun” (_Hic sol novus noster_). Similar figures are employed by Gregory of Nazianzus, Zeno of Verona, Leo the Great, Gregory the Great, etc.[334] Every child knows that Simeon addressed the new-born Messias as “a light to the revelation of the Gentiles,” and, since the Messias is also called by the Prophets the light in the darkness and the Sun of Justice, it is easy to see how such expressions passed into the Church’s liturgy for this festival.[335] It was natural for the Romans to set down the birth-day of this new Sun on the day marked of old time in their Calendar as a _Natalis Solis_, and observed as a festival by all the heathen inhabitants of Rome.[336] The choice of the day cannot be due to the desire to supplant the heathen festival, for it was not a festival of any special importance. But the similarity between the natural fact (the solstice) and the revolution in the spiritual sphere (Christ’s nativity), was sufficient to suggest the idea. It was not necessary to wait for the time of Constantine in order to hit upon this idea. We must now return once more to the usages of the Church of Jerusalem and the festival observed there. The 6th January, indeed, was called in Jerusalem Epiphany, nevertheless the nativity of Christ formed an especially prominent feature of the commemoration.