Just as there is no inquiring by corporeal sight about the essence of fire, because the activity of its essence is seen, though that is not its essence but one is persuaded by its activity that the true essence is seen, so the seers of God's Glory are fully assured without inquiry that they are seeing the Essence of him who is concealed from all and are observing him, moved by a sweet and gentle impulse in tranquil joy, and stirred by serene love joined with wonder. (D21)