Just as mankind has to do with the three realms of nature, he also has to do with three spiritual realms. Now you may say: It is of no consequence whether I believe it or not, for these three kingdoms are not visible, not perceptible. Yes, gentlemen, I have known people, to whom it had to be explained that air exists! They could not believe that there was something like air. When I say to such a person, this is a table – that he can believe, for when he goes to the table, he can knock on the table, and when he looks at it, he sees the table with his own eyes, but he cannot bump into the air. He looks around and says, there is nothing here. However, everyone nowadays admits the existence of air. The existence of air is simply accepted.
In the same way, it will happen that people will come to admit the existence of a spiritual world. Today, people still say: The spiritual realm simply does not exist – in the same manner that the peasants used to say: There is no air. – In my native village the peasants used to say: there is no air at all, only the big-headed people from the city assert that because they want to give the impression that they are so clever; one can walk through it because there is nothing to walk through! – But that was long ago. Today, farmers also accept that air exists. But even the smartest people still don’t recognize that there are spiritual beings everywhere! They will, however, acknowledge it in due time, because otherwise certain things simply will be inexplicable, things that will need to be understood.
Source (German): Rudolf Steiner – GA 353 – Die Geschichte der Menschheit und die Weltanschauungen der Kulturvölker – Dornach, June 25, 1924 (page 306)
Translated by Nesta Carsten-Krüger