“Twenty percent of Americans describe themselves as “spiritual but not religious.” Although the claim seems to annoy believers and atheists equally, separating spirituality from religion is a perfectly reasonable thing to do. It is to assert two important truths simultaneously: Our world is dangerously riven by religious doctrines that all educated people should condemn, and yet there is more to understanding the human condition than science and secular culture generally admit. One purpose of this book is to give both these convictions intellectual and empirical support.Before going any further, I should address the animosity that many readers feel toward the term spiritual. Whenever I use the word, as in referring to meditation as a “spiritual practice,” I hear from fellow skeptics and atheists who think that I have committed a grievous error.The word spirit comes from the Latin spiritus, which is a translation of the Greek pneuma, meaning “breath.” Around the thirteenth century, the term became entangled with beliefs about immaterial souls, supernatural beings, ghosts, and so forth. It acquired other meanings as well: We speak of the spirit of a thing as its most essential principle or of certain volatile substances and liquors as spirits. Nevertheless, many nonbelievers now consider all things “spiritual” to be contaminated by medieval superstition.I do not share their semantic concerns.[1] Yes, to walk the aisles of any “spiritual” bookstore is to confront the yearning and credulity of our species by the yard, but there is no other term—apart from the even more problematic mystical or the more restrictive contemplative—with which to discuss the efforts people make, through meditation, psychedelics, or other means, to fully bring their minds into the present or to induce nonordinary states of consciousness. And no other word links this spectrum of experience to our ethical lives.”