“Arise, be enlightened, Jerusalem, for your Light has come.” This present day of lights has been enlightened for us and consecrated by the Light of Light. He has lain hidden and unknown, but today he has vouchsafed to reveal himself to the world for the enlightenment of all nations. For today he revealed himself to the Chaldeans by the sign of a new star, dedicating in them as in first-fruits the faith of all nations. … Today he manifested his glory before his disciples when by the changing of water into wine he prefigured that ineffable mystery in which by his word the substances of things are changed. … The Light indeed had come; he was in the world, and the world was made through him, but the world did not know him. He was born but he was not known, until this day of light began to manifest him. … Arise, you who sit in darkness; look at the light which has risen up in darkness but is not mastered by the darkness. Draw near to him and be enlightened, in his light you shall see the light; and it will be said to you: “You were once darkness, but now you are light in the Lord.” Look upon the Eternal Light which has tempered itself to your gaze, so that he who dwells in inaccessible light affords access even to weak and bleary eyes. See the Light in a lamp of earthenware, the Sun in a cloud, God in man, the Splendor of Glory and Brightness of Eternal Light in the clay vessel of your flesh.
Guerric of Igny, Liturgical Sermons I, The Second Sermon for the Epiphany, v 1 (CF 8, page 76f.)