III. The Supersensible Being of Man

But what we can experience proves that the province of real knowledge can be widened to include the spiritual world, and that we really can investigate our spirit-soul being which proceeds through births and deaths in repeated lives on earth. A brilliant scientist of the 19th century, Du Bois-Reymond, quite rightly emphasized that the approach to knowledge which has led science to its great successes does not lead us beyond the sphere of nature perceptible to our senses, and therefore could not fathom the depths of existence. He was able to express this inability to know, this “not knowing,” because he himself was immersed only in the faculties of knowledge that can comprehend the outer world of the senses. And he said that if we wanted to undertake something in order to get beyond the natural world, we would enter into supranaturalism, that is, we would immerse ourselves in the spiritual world. But then he said, Where supranaturalism begins, science comes to an end. He did not yet know—and there is good reason why he could not know—that the faculties of our mind which are sharpened and strengthened in observing nature cannot lead to the spiritual world, but that these same faculties first have to transform our thinking and our will so that they can evolve differently from the way they do in ordinary science. Then they have to bring themselves to life, to acquire strength, in order to penetrate up into the spiritual world.