O dawn of the East, brightness of light eternal, and sun of justice: come, and enlighten those who sit in darkness and in the shadow of death.
Today's Antiphon echoes the end of yesterday's, but with a different focus: enlightenment as opposed to release. By placing these two Antiphons together, the Church illustrates that we are in need of both: Come, set us free from our sins; come, teach us what is right that we may not fall back into error again.
The rising of the sun has long caused the East to be viewed, at least symbolically, as the direction from which The Lord comes. We still see this in our worship today: all Catholic churches are (supposed to be) built with the main altar facing East, and we sing hymns like "People Look East" during Advent.
O come Thou Dayspring from on high
And cheer us by Thy drawing nigh;
Disperse the gloomy clouds of night,
And death's dark shadow put to flight.
Rejoice, rejoice; Emmanuel shall come to thee, O Israel.