The main focus of this book is the study of Abraham Ibn Ezra s (1089-1167) scientific thought within the historical and cultural context of his times. His scientific contribution may be understood as the very embodiment of the rise of medieval Hebrew science , a process in which Jewish scholars gradually adopted the holy tongue as a vehicle to express secular and scientific ideas. The first part provides a comprehensive picture of Ibn Ezra s scientific corpus. The second part studies his linguistic strategy. The third and fourth parts study Ibn Ezra s introductions to his scientific treatises and the fifth part is devoted to studying four encounters with Claudius Ptolemy, the main scientific character featuring in Ibn Ezra s literary work.