Arabic Science in Sixteenth-Century Europe: Guillaume Postel (1510-1581) and Arabic Astronomy' George Saliba Key words: Postel, Copemicus, Renaissance, Planetary theories, Arabic Manuscripts, Renaissance Arabists, Islamic astronomy, transmission of ideas, transmission without translation, marginalia. Abstract This paper investigates a hitherto untapped, but quite possible, route of transmission of scientific ideas from the Islamic world to Renaissance Europe. 11 focuses in particular on the role played by the famous orientalist Guillaume Postel (1519-1581) who seems to have studied Arabic astronomical texts dealing with planetary theories and tries to contextualize the marginal notes Postel wrote on the Arabic manuscripts that he had owned. The purpose of this investigation is to demonstrate that the sixteenth century European scientists like Pastel were not in need of Latin translations of Arabic scientific works in order for them to • Research for this project was supported by grants from the National Humanities Center and the Dibner Institute for the History of Science and Technology as well as by a sabbatical1cave from Columbia University for the academic year 1997/98. The Vatican Library and the Bibliolheque Nationa1c de France, Paris, have supplied me with microfilms of Arabic manuscripls in their possession. The support of all Ihose institutions is hereby gratefully acknowledged. [ also wish to express my deepest gratitude to Professor Giorgio Vercellin of Venice who first introduced me 10 Poslel and who allowed me 10 use his private library in Venice. Suhayl 7 (2007) pp. 115-164