"This world is the closed door. It is a barrier. And at the same time it is the way through. Two prisoners whose cells adjoin communicate with each other by knocking on the wall. The wall is the thing which separates them but it is also their means of communication. It is the same with us and God. Every separation is a link. By putting all our desire for good into a thing, we make that thing a condition of our existence. But we do not, on that account, make of it a good. Merely to exist is not enough for us. The essence of created things is to be intermediaries. They are intermediaries leading from one to the other, and there is no end to this."