Book excerpt: Comparison is at the heart of religious studies as a discipline and foundational to the field's methodology. In this book, Arvind Sharma introduces the term "reciprocal illumination" to describe the mutual enlightenment that can occur when a comparison is made between one tradition and another, one method and another, or between a tradition and a method. Developing the concept of reciprocal illumination through historical, phenomenological, and psychological methods, Sharma demonstrates how to use comparison, while avoiding the pitfall of treating it as merely raw material for higher order generalizations.