From a sermon by John the Serene, bishop
The Lord is my light and my salvation; whom shall I fear? How great was that servant who knew how he was given light, whence it came, and what sort of man he was when he was favoured by that light. The light he saw was not that which fades at dusk, but the light which no eye has seen. Souls brightened by this light do not fall into sin or stumble on vice.
Our Lord said: Walk while you have the light in you. What other light did he mean but himself? For it was he who said: I came as a light into the world, so that those who have eyes may not see and the blind may receive the light. The Lord then is our light, the sun of justice and righteousness, who has shone on his Catholic Church spread throughout the world. The prophet spoke as a figure of the Church when he cried: The Lord is my light and my salvation; whom shall I fear?
The spiritual man who has been thus illumined does not limp or leave the path, but bears all things. Glimpsing our true country from afar, he puts up with adversities; he is not saddened by the things of time, but finds his strength in God. He lowers his pride and endures, possessing patience through humility. That true light which enlightens every man who comes into the world bestows itself on those who reverence it, shining where it wills, on whom it wills, and revealing itself according to the will of God the Son.
When this light begins to shine upon the man who sat in darkness and the shadow of death, in the darkness of evil and the shadow of sin, he is shocked, he calls himself to account, repents of his misdeeds in shame, and says: The Lord is my light and my salvation; whom shall I fear? Great is this salvation, my brethren, which fears neither sickness nor lethargy and disregards pain. We should then in the fullest sense not only with our voice but with our very soul cry out, The Lord is my light and my salvation; whom shall I fear? If he enlightens and saves me, whom shall I fear? Even though the dark shadows of evil suggestions crowd about, The Lord is my light. They can approach, but cannot prevail; they can lay siege to our heart, but cannot conquer it. Though the blindness of concupiscence assails us, again we say: The Lord is my light. For he is our strength; he gives himself to us and we give ourselves to him. Hasten to this physician while you can, or you may not be able to find him when you want him.