The people that walked in darkness have seen a great light: they that dwell in the land of the shadow of death, upon them has the light shined.
Read Chapter 9
Ambrose of Milan
AD 397
Hence he was in the shadow of life, whereas sinners are in the shadow of death. According to Isaiah, the people who sinned sat in the shadow of death. For these a light arose, not by the merits of their virtues but by the grace of God. There is no distinction, therefore, between the breath of God and the food of the tree of life. No one can say that he can acquire more by his own efforts than what is granted him by the generosity of God. - "On Paradise 5.29"
Risen. The kingdom of Juda hoped for redress, when they saw the people of Israel humbled, (Haydock) or rather after the defeat of Sennacherib. (Calmet)
Although he filled all things with his invisible majesty, [Christ] came, nevertheless, to those who had not known him, as if from a very remote and deep seclusion. At that time, he took away the blindness of ignorance, as it has been written: “For those sitting in darkness and in the shadow of death, a light has risen.” - "Sermon 25.3"