Not the senses, for if dynamism is true, the senses themselves are made up of simple unextended elements that do not possess, either formally or in an embryonic state, the integral elements of real extension. Nor can the cause be the combined influence of external agencies, because here again are only simple principles whose unextended actions if they come into contact meet in a single indivisible point. No material body, it may be objected, enjoys a real continuity. The most compact masses are full of lacunae or pores interatomic or intermolecular spaces. Our organs of sight misinform us when they represent bodies as continuous wholes.
Extension is therefore apparent.
This we willingly admit, that in the mineral world true continuity belongs only to atoms and to molecules in the compound. We admit that every sensible mass is a collection of minute particles between which we can without difficulty conceive apparent or real intervals of space. If our senses are incapable of perceiving the small interstices that break up the extension of material bodies it is because they are imperfect instruments. But, we argue, this imperfection in no way diminishes the real objectivity of our perception of extension, since every external agent, atomic and molecular mass alike, if taken as a whole, does really possess this quality. Proof Drawn from Unity .