The fact that — to use a colloquialism — people in the future are not going to get much fun out of developments on the physical plane will bring home to them that further evolution must proceed from spiritual forces.
This can be understood only by surveying a lengthy period of evolution and applying what is discovered to experiences that will become more and more general in the future. The trend of forces that will manifest in the well-nigh rhythmical onset of war and destruction — processes of which the present catastrophe is but the beginning — will become only too evident. It is childish to believe that anything connected with this war can bring about a permanent era of peace for humanity on the physical plane. That will not be so. What must come about on the earth is spiritual development.
Source: Rudolf Steiner – GA 193 – Influences of Lucifer/Ahriman: Lecture Three / Bern – 4th November, 1919
Translated by Dorothy S. Osmond