VII. Are There Limits to Knowledge?

Where the metaphysical realist observes a relation between perceptible things (mutual approach through movement, becoming conscious of an object, etc.), there he regards a reality as existing. But the relation that he notices he can, however, express only by means of thinking; he cannot perceive it. The relation, which is purely ideal, is arbitrarily made into something similar to what is perceptible. Thus, according to this line of thought, the real world is composed of perceptual objects which are in ceaseless flux, arising and disappearing, and of imperceptible forces which are permanent and produce the perceptual objects.