V. Can a method of gaining insight into spheres beyond the sense-perceptible world be given a scientific basis?

Observing nature we arrive at certain assumptions and these evoke ideas where we have to say: Here are the corner posts of natural scientific investigation; here we can go no further, here we cannot enter wholly into the phenomena with our thinking, here limits are indeed set to our insight. I could mention many natural scientific concepts that mark the boundaries of knowledge. However, we merely need to take the most commonplace natural scientific ideas and we will find that they are too dense, as it were, so that the questing human mind is unable to penetrate directly into what we have there. We need take only two ideas, for instance—the idea of energy and the idea of matter. We look in vain for clear mathematical concepts concerning the nature of energy and above all also of matter if we base ourselves strictly on observation of the natural world. When we come up against obstacles such as energy and matter, for instance, as we study and observe nature, we get the impression—though in a somewhat different way, in fact a radically different way from that of Kantianism—that such obstacles are met due to our human nature itself. We feel inclined not to investigate the world outside but above all to ask, with regard to these questions: How is the human being constituted? How does it come to be due to our human nature itself that we have to come up against such obstacles when observing nature?