. All men naturally desire to know. A sign of this is the delight we take in the senses; for apart from their usefulness they are loved for themselves, and most of all the sense which operates through the eyes. For not only that we may act, but even when we intend to do nothing, we prefer sight, as we may say, to all the other senses. The reason is that of all the senses this most enables us to know and reveals many differences between things.