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Ptolemy's World

Summary of Ptolemy's Written Works



A Principle of Simplicity

In book III of one of Ptolemy's earlier books, the Almagest, he "laid down the principle that for the best explanation for any kind of phenomena one should adopt the simplest hypothesis that it is possible to establish, provided that it does not contradict in any important respect the results of observation. In other words, never complicate an explanation if it is possible to make it simple" (Brown, 1979, 60). For this alone, Ptolemy is worth remembering.

As a scholar, Ptolemy wrote important texts in astrology, astronomy, biography, geography, music, and optics, as well as a work on the sphere. The exact words that he wrote, however, are not verified. While many manuscripts of Ptolemy’s writings exist, they are dated long after the writer’s lifetime. Some of the earliest writings of Ptolemy survive only in Arabic language manuscripts by unknown translators, rather than in the original Greek. No modern scholarly editions of some of his major writings have been published and some texts Ptolemy wrote are known only by references to them [see the Tour of Maps]. These are the challenges faced by those who study Ptolemy’s writings.