caa a22 4500 477114474 CHVBK 20180405111618.0 cr unu---uuuuu 170330e19960801xx s 000 0 eng 10.1007/BF02327157 doi (NATIONALLICENCE)springer-10.1007/BF02327157 Geminus and the concept of mean motion in Greco-Latin astronomy [Elektronische Daten] [Alan Bowen, Bernard Goldstein] Conclusion: Geminus account of lunar motion in chapter 18 of hisIntroductio astronomiae is, in our view, an important contribution to Greco-Latin astronomy because, in attempting to reconstruct arithmetically (the parameters of) the Moon's motion in longitude, he undermines the task astronomers had hitherto set for themselves. This undermining of a commonly acknowledged view of the purpose of astronomy is articulated in a whole new set of questions concerning the nature and place of both observation and mathematical reasoning in the science of the heavens. Yet, one must not overlook the fact thatGeminus reconstruction also indicates resources for addressing these questions. Of these resources, the most powerful proved to be the idea that irregular motion could be quantified as a systematic departure from a mean motion, and the idea that observational data could be organized and structured by means of genetic arithmetical reconstructions. But, since we limit our attention to extant treatises and decline to speculate about works or parts of works that have not survived, we must say that it would takePtolemy to discern the new direction for astronomy thatGeminus opened up and to pursue it. In part, this involved straightening out the conflated conception of mean motion in chapter 18 — the μεση κίνησίςqua arithmetic mean daily displacement can only be anapparent lunar motion in longitude and not one the Moonreally makes, but the same need not be true of the μέση κίνησιςqua periodic mean daily displacement — and determining its proper relation to real and apparent planetary motion. Indeed,Ptolemy's genius lay, we think, in seeing that even though, in assimilating Babylonian astronomy, earlier and contemporary Greco-Latin writers betrayed a confused, inconsistent, and unsophisticated grasp of the proper role of arithmetic, geometry, and observation in astronomical argument [seeBowen 1994], the solution lay in a mathematical reconstruction of the observed celestial motions, in which mean motion played an essential role. Springer-Verlag, 1996 Bowen Alan Institute for Research in Classical Philosophy and Science, Princeton, USA aut Goldstein Bernard Institute for Research in Classical Philosophy and Science, Princeton, USA aut Archive for History of Exact Sciences Springer-Verlag 50/2(1996-08-01), 157-185 0003-9519 50:2<157 1996 50 407 https://doi.org/10.1007/BF02327157 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02327157 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bowen Alan Institute for Research in Classical Philosophy and Science, Princeton, USA aut NATIONALLICENCE 700 1- Goldstein Bernard Institute for Research in Classical Philosophy and Science, Princeton, USA aut NATIONALLICENCE 773 0- Archive for History of Exact Sciences Springer-Verlag 50/2(1996-08-01), 157-185 0003-9519 50:2<157 1996 50 407 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer