Spirituality remains the great hole in secularism, humanism, rationalism, atheism, and all the other defensive postures that reasonable men and women strike in the presence of unreasonable faith. People on both sides of this divide imagine that visionary experience has no place within the context of science—apart from the corridors of a mental hospital. Until we can talk about spirituality in rational terms—acknowledging the validity of self-transcendence—our world will remain shattered by dogmatism. This book has been my attempt to begin such a conversation.