Modern psychology is at an impasse as it searches anxiously for new therapies to address the increasing occurrence of mental illness in contemporary society. In this groundbreaking anthology, leading authors from the perennialist school, including Huston Smith, Seyyed Hossein Nasr, and Frithjof Schuon, draw on the age-old insights of the world's wisdom traditions to argue that modern psychology—behaviorism, psychoanalysis, humanistic and transpersonal psychology—overlooks the specifically spiritual factors contributing to mental health and illness.