 intelligible extension becomes visible and represents a certain body in particular only by means of color, because it is only by the variety of colors that we judge the difference between the objects we see…. [A]s the sensations of color are essentially different, by means of them we judge the variety of bodies. If I distinguish your hand from your coat and both from the air surrounding them, this is because the sensations of light or color that I have of them are very different (Dialogue 1, OC 12:46–7; JS 17).