A lot to think about in that one little line. A lot to think about in the dance of shadow and light, which moves all around us and within. The more we understand about how we house dark and light inside our own souls, the more we can understand its movement through the world.
That’s a lot to look at, a lot to be accountable for, too, over time and in eternity. No wonder we are always only beginners.
It reminds me a little bit of Switchfoot: "The shadow proves the sunshine; let my shadows prove the Sunshine."