Faith is the doorway to the mysteries. What the eyes of the body are for physical objects, faith is for the hidden eyes of the soul. Just as we have two bodily eyes, so we have two spiritual eyes, and each has its own way of seeing. With one we see the glory of God hidden in creatures: with the other we contemplate the glory of God's holy nature when he deigns to give us access to the mysteries.
ISAAC OF NINEVEH Ascetic Treatises, 72