III. The World as Illusion

It is apparent that for such a conception all phenomena of the world are divided into two completely separated parts, into a world of motions that is independent of the special nature of our faculty of perception, and a world of subjective states that are there only within the perceiving subjects. This view has been expressed sharply and pointedly by the physiologist, Du Bois-Reymond (1818–96), in his lecture, On the Limits of Natural Science, which he gave at the forty-fifth assembly of German naturalists and physicians on August 14, 1872 in Leipzig. Natural science is the reduction of processes we perceive in the world to motions of the smallest physical particles of a “dissolution of natural processes into mechanics of atoms,” for it is a “psychological fact of experience that, wherever such a dissolution is successful” our need for explanation is for the time being satisfied. Moreover, it is a known fact that our nervous system and our brain are of a material nature. The processes that take place within them can also be only processes of motion. When sound or light waves are transmitted to my sense organs and from there to my brain, they can here also be nothing but motions. I can only say that in my brain a certain process of motion goes on, and I have simultaneously the sensation “red.” For if it is meaningless to say of cinnabar that it is red, it is not less meaningless to say of a motion of the brain particles that it is bright or dark, green or red. “Mute and dark in itself, that is to say, without qualities,” such is the world according to the view that has been obtained through the natural scientific conception, which