O Oriens

English translation:
O Eastern Morning Star,
splendor of eternal light and Sun of justice:
Come! and illuminate those sitting in darkness and the shadow of death.

O oriens - this reflects the early Christian practice of all facing the same way to pray, even during Mass, to pray towards the East, the direction from which the Lord will come. They in joy prayed for his coming and showed this in their posture. This is why in the old days the priest who face the same way as the people during Mass (hence incidently he would have his back to them).