VI. The Human Individuality

Most difficult of all to overcome are the so-called physiological proofs of the subjectivity of our perceptions. If I press the skin of my body, I perceive this as a sensation of pressure. Such pressure will be perceived by the eye as light, by the ear as sound. For example, by the eye I perceive an electric shock as light, by the ear as sound, by the nerves of the skin as shock, and by the nose as a phosphoric smell. What follows from these facts? Only this: that when I perceive an electric shock (or a pressure, as the case may be) followed by a light quality or a sound, respectively, or a certain smell, etc., then, if no eye were present, no perception of a light quality would accompany the perception of mechanical vibrations in my environment; without the presence of the ear, no perception of sound, etc. But what right has one to say that in the absence of sense-organs, the whole process would not exist at all? From the fact that an electrical process calls forth light in the eye, those who conclude that outside our organism, what we sense as light is only a mechanical process of motion, forget that they are only passing from one perception to another, and nowhere to something over and above perceptions. Just as we can say that the eye perceives a mechanical process of motion in its surroundings as light, we can also say that a regulated change in an object is perceived by us as a process of motion. If I draw twelve pictures of a horse on the circumference of a rotating disc, reproducing exactly the positions which the horse's body successively assumes in movement, then by rotating the disc I can produce the illusion of movement. I need only look through an opening in such a way that in the proper intervals I see the successive positions of the horse. I see, not twelve separate pictures of a horse, but the picture of a single galloping horse.