Kings 

There are two levels of visibility: the visibility of the subject and that of the instrument through which the subject acts.
The mystery is actually present in the visible object, it is also actually present to him who sees the visible object, not indeed in the sense that he thereby perceives the mystery as it is in itself, but in the sense that when by faith he is apprised of the union of the two elements, he knows upon seeing the visible object that he actually has the mystery before him.
- Benoît-Dominique de La Soujeole, The Mystery of the Church