Rudolf Steiner: "Humanity has had to experience in relation to the science of nature the extension of its horizons. Giordano Bruno showed men that there is not only the earth, but many other worlds in cosmic space. Spiritual science shows men that there is not only earthly life, but many earthly lives. Before Giordano Bruno men believed that there was a fixed boundary up in the sky. Giordano Bruno showed that there is no boundary, that the blue of the sky is not a limit. Spiritual science shows that birth and death are not there, but that we introduce them into life through the limitation of our understanding. Thus the gulf between the physical and the spiritual can be bridged over."