Religious and spiritual experiences (RSEs) are a puzzle. Some people receive them gratefully as reliable ways to discover the deepest truths about reality. Others approach them warily, as misleading side-effects of the human brain's spectacular virtual-reality processing system. Great passion surrounds such opposed convictions, because the stakes are high. The first group defends the very meaning of human life, after all, while the second group protects the world from dangerous fanaticism. The passion on all sides makes patient inquiry exceptionally difficult but that has not stopped intellectuals from trying. As a result, endless streams of reflection on the puzzle, most promising impartial handling of evidence and judicious interpretation, pour into the present from all of the world's literate philosophical and religious traditions. In our own time, studies of the social psychology and neuroscience of these experiences join the confluence of wisdom, sometimes naively claiming to offer the last word on the subject.

No approach, no researcher, no writer, and no book will speak the last word on RSEs. Advance in understanding occurs at the margins, to be sure, but the central puzzle remains because there are no knock-down refutations of the best versions of competing interpretations. The first challenge facing the interpreter of RSEs is therefore to avoid simple-minded thinking on the subject. This is more difficult than it may seem at first glance. It involves committing to working carefully across the relevant disciplines and traditions, thereby properly preparing the interpreter to avoid pitfalls into which less diligent inquirers routinely fall.