1890s William James says that the self has four layers: the biological, the material, the social, and the spiritual.
1956 Abraham Maslow stresses the importance of “peak experiences” in the route to self-actualization.
1960s British psychiatrist Humphry Osmond coins the term “psychedelic” to describe the emotional effects of the drugs LSD and mescaline.
1962 In his “Good Friday Experiment,” US psychiatrist and theologian Walter Pahnke tests if psychedelic drugs can deepen religious experience.
1972 US psychologist Robert E. Ornstein argues in The Psychology of Consciousness that only personal experience ...