Seyyed Hossein Nasr is a renowned scholar of Islamic science, philosophy, and religion and one of the leading contemporary representatives of traditional or "perennial" philosophy. The work of the traditionalists is not widely known, in part because the early and chief expositors of the movement, René Guénon and Frithjof Schuon, were not academics--indeed, they were highly critical of academic approaches to philosophy and religion. But their work also tends to receive less attention because their assumptions about the nature of reality and about the ability of human beings to know that reality are fundamentally opposed to modern reductionism and rationalism. Nasr's work has played a central role in bringing traditionalist ideas into the realm of academic debate. His works tend to focus on Persian and Islamic topics, but even in these specialized writings Nasr's concern for certain key ideas that he believes underlie every premodern...