The attempt to identify the emotional sources of religion goes back to antiquity. In an exploration that bridges science and spirituality, Robert C. Fuller makes the convincing case that a sense of wonder is a principal source of humanity's belief in the existence of an unseen order of life. Like no other emotion, Fuller argues, wonder prompts us to pause, admire, and open our hearts and minds. With a voice that seamlessly blends the scientific and the contemplative, Fuller defines wonder in keeping with the tradition of Socrates--as an emotion related to curiosity and awe that stimulates engagement with the immediate physical world. He draws on the natural and social sciences to explain how wonder can, at the same time, elicit belief in the existence of a more-than-physical reality. Chapters examining emotions in evolutionary biology and the importance of wonder in human cognitive development alternate with chapters on John Muir, William James, and Rachel Carson, whom Fuller identifies as "exemplars of wonder." The writings and lives of these individuals express a functional side of emotion: that the very survival of life on earth today may depend on the empathy, compassion, and care that are aroused by a sense of wonder. Forging new pathways between the social sciences, philosophy, belief, and cultural history, Wonder deepens our understanding of the complex sources of personal spirituality and fulfillment.