The universe or cosmos consists thus of two kinds of worlds: the physical world and the spiritual world. All galaxies, suns and planets and everything that, in connection with these worlds, is visible for the physical senses thus constitutes the physical world. Everything that lies outside these physically visible phenomena, which means the dark empty space of the universe, makes up the spiritual world. When this world shows itself as empty space it is, as mentioned above, merely because the details of this world are inaccessible to the physical senses. But for the highest spiritual abilities or psychic senses the spiritual world does not constitute an empty space. For these senses the physical empty space of the universe becomes a gigantic radiant world full of life, light and joy.
      We will not go into this world in more detail here since, in other lectures and writings, we have done so. Here we will merely shed yet another little ray of light upon the physical side: the empty space of the universe. People ordinarily believe that this empty space is also a physical world, which one will physically be able to live in and move in in the same way as one can live and move in the physical area that is called the Earth. Many people actually believe that one will be able to build vehicles, spaceships of a kind, by means of which regular connections to other planets and solar systems could be established. The foreign worlds could thus become fabulous tourist attractions, just as import and export between the planets must also thereby become a fact. We see here how stupendously the imagination can run wild when it deals with areas whose true structure the source of this imagination does not know. These people do not understand at all that it is just as impossible for the animal being to live in the empty space of the universe as it is impossible for an ordinary fly to live at the bottom of the ocean and for a deep-sea fish to live in a burning desert.
      The physical parts of life for all living beings are totally dependant on the opportunities for living to which their physical organisms give them access. How could living beings come to experience opportunities for life that their organisms are not built to be able to give rise to?