"(...) the consciousness that the walls shut off the outer world would vanish. Now, what appears first is not merely that he sees the neighboring houses outside, that the walls become like glass, but in the sphere which opens up there is a world of purely spiritual phenomena; spiritual facts and spiritual figures become visible. We need only reflect that behind everything around us physically there are spiritual beings and facts... (...) In a red room, other beings become visible than in a blue room, when one penetrates to them by means of colour. We may now ask: what happens if one is not clairvoyant? That which the clairvoyant does consciously is done unconsciously by the etheric body of a person not clairvoyantly trained; it enters a certain relationship with the same beings."
[Lecture given by Steiner in dedication of the Stuttgart House under which lay his Rosicrucian temple. 15 October 1911. Art Inspired by Rudolf Steiner, John Fletcher Mercury Arts Publications 1987]