Keys to the Beyond is a guide to the thought of Frithjof Schuon (1907–1998), a Swiss philosopher of religion. His work has generally not been taken very seriously within the formal academic study of religion, but it has nonetheless been widely influential, both within and beyond academia. The scholarly status of Schuon’s work, then, is something of a paradox: actually influential, but also generally ignored, and certainly inadequately discussed. The same is true of the work of the French philosopher of religion and esotericist René Guénon (1886–1951), the single most important influence on Schuon. The work of Guénon, Schuon, and some others is usually described as “Traditionalism” or “Perennialism,” and is a particular instance and development of those two broad forms of thought.Schuon’s ideas may be of particular interest to readers of Nova Religio because he was not only a philosopher of religion but also the founder and leader of a group that can be understood as a new religious movement. Its participants would strongly reject such a characterization, however, on the grounds that the understandings and practices of the group were traditional rather than new, and esoteric rather than religious. Author Patrick Laude does not discuss this group in his book, but it is examined in other scholarly work, including my own studies. Laude’s book instead focuses on Schuon’s philosophy.Schuon was a prolific writer, and 64 of his books are listed in the bibliography of Keys to the Beyond, which gives both first editions in German or French, and English translations. These works include posthumous compilations. There is a lot of material, then, and a definite need for a book, such as this, written by a scholar who knows Schuon’s writings well. Some might object that Laude knows Schuon’s writings too well to approach them entirely objectively, but that is in fact not a problem, because the book’s objective is expository and explanatory, not evaluative.The book consists of an introduction and ten chapters, the first four of which consider fundamental aspects of Schuon’s thought, including three based around the discussion of Sanskrit terms that are of particular importance to Schuon. Like Guénon, Schuon drew strongly on the Advaita Vedanta. These chapters are followed by two chapters looking in detail at Schuon’s understanding of the two religions that were most important for him personally and for his followers, Christianity and Islam. The chapter on Islam is especially interesting because the group that Schuon led was predominantly Sufi, and the nature of relations between Schuon and Islam has been the subject of much debate. Laude’s contribution to this debate is well-argued and convincing. The book’s next three chapters deal with three related special topics: Schuon’s conception of the Divine feminine, his understanding of Yin and Yang, and his approach to the issue of sexuality. Then comes a final chapter on esoteric ecumenism, which partly compares Schuon’s thought to the better-known thought of the Anglo-American philosopher of religion and academic John Hick (1922–2012), and partly discusses the relationship between Schuon’s thought and approaches that are common within the academic field of religious studies.One of Laude’s hopes is that this book might help Schuon’s philosophy assume a place in the academy comparable to that occupied, for example, by the thinking of Hick. It would certainly be good if scholars of religion and philosophy paid more attention to this system, not only because of the impact it has had, but also because it is sophisticated and interesting. Given that Schuon’s thought is, as Laude recognizes, quintessentially essentialist, however, it is very much at odds with prevailing approaches.There are, inevitably, some areas of Schuon’s thought that are not covered in this book. I myself would like to have read more on Schuon’s views on Native American spirituality and on art. But many things certainly had to be omitted to keep a book, such as this to a manageable length, and on the whole I think Laude made the right decisions and selections. The result is a major achievement, succinctly synthesizing Schuon’s work into one volume.The book’s introduction notes that it assumes some prior knowledge of Schuon’s thought, and therefore “might arguably be most helpful to those who have already entered Schuon’s conceptual world” (10). Some sections might work well with advanced undergraduate and graduate students. For most readers without any prior knowledge of Schuon’s work, however, this book might be hard going. It is not really a general introduction, except, perhaps, for those who are already familiar with the thought of other philosophers of religion. For a reader who, like this reviewer, does have some prior knowledge, the book provides an expert and systematic review of the most important elements of Schuon’s thought. It is not always easy reading but neither is Schuon himself, and philosophy is not really meant to be easy reading.