It seemed like a good metaphor for writing a novel. However much we may plan the book before hand, we're still writing into the darkness, only able to see a short distance in front of us at any one moment. We write, and we write, trusting that we will make it to our destination even though we can't see clearly where we are going.
Alan Bennett wrote in his diaries, "We don't know what we're writing until we've written it." We just have to follow the lights and carry on writing until we're home.