Their main concern was ‘to save the appearances’. The original meaning of this ominous phrase was that a theory must do justice to the observed phenomena or ‘appearances’; in plain words, that it must agree with the facts. But gradually, the phrase came to mean something different. The astronomer ‘saved’ the phenomena if he succeeded in inventing a hypothesis which resolved the irregular motions of the planets along irregularly shaped orbits into regular motions along circular orbits – regardless whether the hypothesis was true or not, i.e. whether it was physically possible or not. Astronomy,
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