And how much human nature loves the knowledge of its existence, and how it shrinks from being deceived, will be sufficiently understood from this fact, that every man prefers to grieve in a sane mind, rather than to be glad in madness. And this grand and wonderful instinct belongs to men alone of all animals; for, though some of them have keener eyesight than ourselves for this world's light, they cannot attain to that spiritual light with which our mind is somehow irradiated, so that we can form right judgments of all things. For our power to judge is proportioned to our acceptance of this light. Nevertheless, the irrational animals, though they have not knowledge, have certainly something resembling knowledge; whereas the other material things are said to be sensible, not because they have senses, but because they are the objects of our senses. Yet among plants, their nourishment and generation have some resemblance to sensible life. However, both these and all material things have their causes hidden in their nature; but their outward forms, which lend beauty to this visible structure of the world, are perceived by our senses, so that they seem to wish to compensate for their own want of knowledge by providing us with knowledge. But we perceive them by our bodily senses in such a way that we do not judge of them by these senses. For we have another and far superior sense, belonging to the inner man, by which we perceive what things are just, and what unjust,—just by means of an intelligible idea, unjust by the want of it. This sense is aided in its functions neither by the eyesight, nor by the orifice of the ear, nor by the air-holes of the nostrils, nor by the palate's taste, nor by any bodily touch. By it I am assured both that I am, and that I know this; and these two I love, and in the same manner I am assured that I love them.