“Again Jesus spoke to them, saying, ‘I am the light of the world; he who follows me will not walk in darkness, but will have the light of life (τὸ φῶς τῆς ζωῆς).’” (Jn 8: 12)
What is “light”? In physical terms it is that which enables us to see. In theological terms it is God Himself, whose presence enables me to see things as they are, rather than how I wish or imagine them to be.
Let me not walk in darkness today, because I don’t have to. “God is the Lord and has revealed Himself to us.” (Ps 117: 27) Blessed is He Who comes, and blessed are we who receive Him, and choose to walk in His light and lightness.