4406. As the sight of the eye corresponds to the understanding, for this reason sight is attributed to the understanding also, and is called intellectual sight. Moreover the things which a man observes are called the objects of this sight; and also in ordinary discourse we say that things are "seen" when they are understood; and light and enlightenment, and the consequent clearness, are also predicated of the understanding; and on the other hand, so are shades and darkness, and the consequent obscurity. It is on account of the correspondence that these and the like things have come into common speech among men; for man's spirit is in the light of heaven, and his body is in the light of the world, and the spirit is that which lives in the body, and also is that which thinks. Hence many things that are interior have fallen in this way into words.