The nine papers collected here explore a broad range of sources for texts from the classical period of Arabic philosophy, and a broad range of influence exerted by these texts. By the 'classical period' is meant that part of the Arabic philosophical tradition normally included in the canon of 'medieval' philosophy. It begins in the ninth century, which is when the impact of Greek philosophical and scientific works began to be felt, thanks to their translation under the 'Abbasid caliphs, and ends in the twelfth century. This volume focuses on the influences felt by, and exerted by, the four main philosophers of this period: al-Kindi, al-Farabi, Avicenna, and Averroes. But the historical range covered extends well past the twelfth century, into Latin Renaissance philosophy and Islamic philosophy of the seventeenth century. Philosophical themes include human psychology, logic, the influence of Neoplatonism, and problems in Aristotelian natural philosophy.