It doesn't even need to be seen. What is that?

But this one is never hidden, but never inside. It doesn't need sight to be apparent, what is that? In the world it is said seeing is believing. This one doesn't even need seeing. Now belief of that matter. It is that apparent that it doesn't even need to be seen. What is that? That is the only one. Everything else that needs to be seen to become apparent is not real.