Light and Life

In the natural realm, we depend on the sun’s light for illumination. Our physical bodies have eyes and therefore we need light to show us where we are and where we need to go. We also need it to help us see and avoid or evade the myriad dangers around us. We have good reason to have a natural fear of the dark, because it conceals those dangers. Darkness veils creatures, inanimate objects, and environments that can seriously injure or kill us. And in the dark, we don’t know the way to go.
But the sun also literally gives our bodies life. In order to survive, we eat plants that eat light, or we eat animals that eat plants that eat light. Our bodies also absorb vital nutrients directly from sunlight and would not be able to survive without the heating effect that this electromagnetic radiance produces. 
So, natural light shows us the way we should go, reveals what’s true about our surroundings, and literally gives and sustains our bodily lives. 
The same is true of the divine spiritual light David refers to in Psalm 36:9, the light that God is (1 John 1:5) and the light that God gives(Revelation 21:23–25) frequently described in Scripture: 
Divine light shows us the way to go. “Your word is a lamp to my feet and a light to my path” (Psalm 119:105). 
Divine light reveals what’s true about our spiritual surroundings. “The people dwelling in darkness have seen a great light, and for those dwelling in the region and shadow of death, on them a light has dawned” (Matthew 4:16).
Divine light literally gives us spiritual life: “God, who said, ‘Let light shine out of darkness,’ has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ” (2 Corinthians 4:6).
It is no accident that David paired “life” and “light” together in Psalm 36:9. For spiritual light and life, like natural light and life, are woven inextricably together.