The Sleepwalkers: A History of Man's Changing Vision of the Universe

by Arthur Koestler

Yet even toward the end of the book (in chapter 60), long after he had found the correct law, Kepler speaks of the inverse ratio postulate as if it were true not only for Earth, but also for Mars. He could not deny, even to himself, that the hypothesis was incorrect;he could only forget it. Which he promptly did. Why? Because, though he knew that the postulate was bad geometry, it made good physics to him, and therefore ought to be true. The problem of the planetary orbits had been hopelessly bogged down in its purely geometrical frame of reference, and when Kepler realized that he could not get it unstuck, he tore it out of that frame and removed it into the field of physics. This operation of removing a problem from its traditional context and placing it into a new one, looking at it through glasses of a different colour as it were, has always seemed to me of the very essence of the creative process.35 It leads not only to a revaluation of the problem itself, but often to a synthesis of much wider consequences, brought about by a fusion of the two previously unrelated frames of reference. In our case, the orbit of Mars became the unifying link between the two formerly separate realms of physics and cosmology.