Timothy Leary was one of the most famous countercultural icons of the 1960s. In 1957, the Harvard psychologist experienced a "profound transcendent experience" while taking hallucinogens in Mexico. No longer content with his work in personality assessment, Leary began advocating the psychotherapeutic and spiritual benefits of LSD. His experiments with LSD often involved students and wild "tripping" parties, which eventually led to his dismissal from Harvard. With patronage from heirs of the Mellon fortune, Leary continued his experiments and prolific writing career at a rambling estate in upstate New York known as Millbrook. In 1967, Leary spoke at a San Francisco "Be-In," where he coined the phrase "Turn on, tune in, and drop out." Labeled "The Most Dangerous Man in America," Leary had many run-ins with the law and served several prison sentences. He died of prostate cancer in 1996; the following year seven grams of his ashes were launched into space aboard a Pegasus rocket.

Ralph Metzner, Ph.D., was a psychologist who explored states of consciousness and transformational practices throughout his career. As a graduate student at Harvard (where he received a Ph.D. in clinical psychology), he worked with Timothy Leary and Richard Alpert (later Ram Dass) on the Harvard Psilocybin Projects. He co-wrote The Psychedelic Experience and was editor of The Psychedelic Review. He was a professor of psychology at the California Institute of Integral Studies. He was also president of the Green Earth Foundation, a non-profit organization dedicated to reconnecting humans and the environment. The author of over a dozen books, Dr. Metzner maintained a part-time psychotherapy practice and conducted numerous workshops on consciousness transformation, both nationally and internationally.

Gunther M. Weil, Ph.D., is an educator, psychologist and consultant who has provided personal growth training for executives and their organizations throughout the world. He is also a 30-year practitioner and teacher of Tai Chi Chuan and an internationally recognized master teacher of Qigong. Weil served as a Fullbright Scholar in Europe and received his doctorate from Harvard University in 1965. His early professional mentors included Carl Rogers, the creator of Client Centered Psychotherapy, and Abraham Maslow, the father of Humanistic Psychology. He was invited by Maslow to teach at Brandeis University and he also received faculty and administrative appointments at Boston College and the University of Massachusetts.