"I am the light of the world."
Light is used throughout Scripture in reference to God. The creation story in Genesis 1 begins the great narrative of the Bible with the clear fact that God created light days before creating anything to "produce" that light. What?! Go look! God makes light on the first day! The sun and other stars don't come along till day four! In Revelation 22:5, John informs his readers that there will be no more need for the sun. The light God provides is an all encompassing light. There is NO darkness, not one shadow!
With that in mind, what does it mean when Jesus says, "You are the light of the world" in Matthew 5:14? What does that mean for your interaction with your neighbors? Coworkers? Etc.?