The great question in the first instance then becomes this: do such facts exist? Do real phenomena that cannot be weighed and measured exist? Are there things beyond time and space, things that really exist and can be perceived only in quite a different way than in the form of metres, kilos or wavelengths, or in the form of stone, water or air? Yes, such facts do exist. How else would we able to think or understand? Human thought itself is neither stone, water nor air, is it? One will certainly arrive at being able to measure it in terms of "wavelength", but can such a measure be any explanation of what thought really is? And are there not, within the psychic side of living beings, so many facts that they, so to speak, constitute a whole world, indeed a whole plane of existence? It is this plane of existence or this psychic side of the physical world that, in the religions, is called "the spiritual world".
      Every normal human being is familiar with thinking; he knows that it is something that takes place in the brain, but how this process is really triggered off and what thought is, he knows extremely little, or nothing at all, about. This, the existence of thought, occurs alongside the three other states of matter: stone, water and air. Under the principle "stone" is here to be understood all solid substances. All liquid substances are to be grouped under the principle "water", just as we, under the principle "air", include all kinds of gases or gaseous substances.
      While material or physical science is now beginning to feel familiar with the variations of matter within these three principles, it is still to the highest degree fumbling and searching for the fourth principle revealed through these three principles: "thought" or "the thought-world". As material science can regard only weights and measures, concepts of time and space, volume and degrees of speed as the foundations for a real "science", it cannot, with this attitude, include "the thought-world", or the fourth principle of matter, under what it perceives as science. A thought cannot be weighed or measured in metres, litres or kilos. And even in such cases where one might really succeed, through a suitable measuring device, in ascertaining a reaction of thought, this discovery would only be an experience of the outer material effects of the kind of energy of the thought, that is, a new experience of degrees of vibration or speed. But the real nature or innermost being of the thought would still remain an enigma, would still be a mystery. That one can ascertain the thought as a kind of electric vibration, force or movement does not of course remove the mystery and cannot possibly be a satisfactory answer to the question about its innermost analysis. The fact that the thought is an electrical vibration or wavelength, or the like, does not of course explain how it comes about that it is perceived as desire, will, joy or sorrow. To register the reactions to these occurrences in the brain as degrees of vibration or wavelength is only an experience of new numerical results. This experience can create with this only a further extension of the already existing ocean of numbers and results in weights and measures of material science.