The Bible is full of references to Jesus - The Light of the World - coming into the darkness of the world.
This morning I was reading Isaiah 9:2. "The people who walk in darkness shall see a great Light—a Light that will shine on all those who live in the land of the shadow of death." I began pondering how I would illustrate Jesus embodying light in utter darkness, this thing that is true in the spiritual realm but invisible in the material realm.
Then I had a "duh" moment. THAT is exactly what all of those medieval and renaissance artists were trying to convey with the halos around Jesus. I had always sort of connected the halos with cheesy Precious Moments imagery. Back in the day, this idea hadn't yet saturated the collective consciousness and become cartoonhy. I realized that these artists who came up with the original halo idea were really very creative. Looking on things unseen.
Notice how in this painting by an unknown 14th century artist, Jesus has the major halo and the disciples have lesser ones, since they (and we) are reflecting HIM. Genius.