I cannot form a picture upon something which is moving; that something must be stationary, because the rays of light which I throw on it are moving, and these moving rays of light, must be gathered, unified, co-ordinated, and completed upon something which is stationary. Similar is the case with the sensations which these organs of ours are carrying inside and presenting to the mind, and which the mind in its turn is presenting to the intellect. This process will not be complete unless there is something permanent in the background upon which the picture, as it were, may be formed, upon which we may unify all the different impressions. What is it that gives unity to the changing whole of our being? What is it that keeps up the identity of the moving thing moment after moment? What is it upon which all our different impressions are pieced together, upon which the perceptions, as it were, come together, reside, and form a united whole? We have found that to serve this end there must be something, and we also see that that something must be, relatively to the body and mind, motionless. The sheet of cloth upon which the camera throws the picture is, relatively to the rays of light, motionless, else there will be no picture. That is to say, the perceiver must be an individual. This something upon which the mind is painting all these pictures, this something upon which our sensations, carried by the mind and intellect, are placed and grouped and formed into a unity, is what is called the soul of man.