In certain periods of the world's history man has discovered a finer substance; scientists have come to atoms and electrons and still finer particles. But then what? Then, they say, there is nothing. The fact is that man wishes to perceive that which is called vacuum by the same method with which he perceives substance, and this is not possible. Therefore, however far he may advance in the discovery of life, he can only reach the most extremely fine substance. In this way people may search for thousands of years and they may succeed in finding a still finer substance, perhaps even a most useful substance, but it will still be a substance and not a vacuum.