Conclusion

This chapter summarizes key themes and presents some final thoughts. It suggests that Ptolemy attempted to quantify his astronomical models because astronomy, like astrology, is by definition a predictive science. Ptolemy defines astronomy in juxtaposition with astrology in the first chapter of the Tetrabiblos. Consistent with Almagest 1.1, he claims that the judgments of astronomy are sure, whereas astrology, like every other study of material quality, is conjectural. Yet, the claims of astrology are still possible, as opposed to impossible, and therefore they merit study. The chapter then considers the question of whether Ptolemy's his metaphysics, epistemology, and ethics were influential.