The ethical ideas on which civilization rests have been wandering about the world, poverty-stricken and homeless. No theory of the universe has been advanced which can give them solid foundation; in fact not one has made its appearance which can claim for itself solidity and inner consistency. The age of philosophical dogmatism had come to an end, and after that nothing was recognized as truth except the science which described reality. Complete theories of the universe no longer appeared as fixed stars; they were regarded as resting on hypothesis, and ranked no higher than comets.

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