Ibn Sina - Avicenna in Latin - (980-1037) played a considerable role in the development of both eastern and western philosophy and science. His contributions to the fields of logic, natural science, psychology, metaphysics and theology and even medicine are difficult to overstate. The great Islamic philosopher al-Ghazali thought that if one could show the incoherence of Avicenna's thought, then one would have shown the incoherence of philosophy in general. No other author is directly cited by Thomas Aquinas more often than Avicenna. But Avicenna's significance and influence do not stop with the medieval period. His logic, natural philosophy, and metaphysics are still taught in the Islamic world as living philosophy. And many contemporary Catholic and evangelical Christian philosophers still come under his influence through Aquinas's work. Despite Avicenna's important place in the history of ideas, however, there is no single volume that both does justice to the complete range of his intellectual activity and provides a rigorous analysis of the philosophical content of his thought. This book is designed to remedy that lack. It will provide a general introduction to Avicenna's intellectual system and offer a careful philosophical analysis of most of the major aspects of his thought, presented in such a way as to be accessible to students as well as serving as a resource for specialists in Islamic studies, philosophers, and historians of science.