Ralph Metzner (1936–2019) obtained his Ph.D. in Clinical Psychology at Harvard University, where he collaborated with Timothy Leary and Richard Alpert on psychedelic research. He was Professor Emeritus at the California Institute of Integral Studies in San Francisco and president and co-founder of the Green Earth Foundation. Dr. Metzner is the author of numerous books, including Overtones and Undercurrents, Searching for the Philosophers’ Stone, and Green Psychology.