Book excerpt: Altered consciousness is one of humanity's most mystical and life-altering aspects. These remarkable changes in mental state have understandably been a topic of general interest and scientific inquiry across time. Beyond simply satisfying our curiosity, however, studies focused upon altered consciousness can also bring valuable insights into our experience, biology, and culture. This unprecedented set of books will intrigue anyone interested in psychology, biology and neurology, science, history, arts and the humanities, and literature on consciousness, from general readers to scholar and researchers. An impressive collection of international contributors address altered states of consciousness from the perspectives of history, evolution, psychology, culture, literature, human biology, contemporary science, and society, seeking to illuminate the causes, effects, and meanings of altered consciousness. The first volume provides an introduction and centers on the importance of altered states in history, culture, and the humanities, while the second volume presents biological and psychological perspectives on altered consciousness and examines their potential for healing and pathology.