Heard was a guide and mentor to numerous well-known Americans, including Clare Boothe Luce and Bill Wilson, co-founder of Alcoholics Anonymous, in the 1950s and 1960s. His work was a forerunner of, and influence on, the consciousness-development movement that has spread in the Western world since the 1960s.
He first embarked as a book author in 1924, but The Ascent of Humanity, published in 1929, marked his first foray into public acclaim as it received the British Academy’s Hertz Prize. From 1930 to 1934 he served as a science and current-affairs commentator for the BBC. In 1936 he played a minor part in the development of the Peace Pledge Union. In 1937 he emigrated to the United States, accompanied by Aldous Huxley and Huxley's wife Maria, to give some lectures at Duke University. In the U.S., Heard's main activities were writing, lecturing, and the occasional radio and TV appearance. His pattern was set as an informed individual who recognized no conflict among history, science, literature, and theology.
Heard turned down the offer of a post at Duke, settling in California. In 1942 he founded Trabuco College (in the Santa Ana Mountains) as a facility where comparative religion studies and practices could be pursued.
Heard was the first among a group of literati friends (several others of whom, including Christopher Isherwood, were also originally British) to discover Swami Prabhavananda and Vedanta. Heard became an initiate of Vedanta. Like the outlook of his friend Aldous Huxley (another in this circle), the essence of Heard’s mature outlook was that a human being can effectively pursue intentional evolution of consciousness. He maintained a regular discipline of meditation, along the lines of yoga, for many years.
In the 1950s, Heard tried LSD and felt that, used properly, it had strong potential to 'enlarge Man's mind' by allowing a person to see beyond his ego. In late August 1956, Alcoholics Anonymous founder Bill Wilson first took LSD — under Heard's guidance and with the officiating presence of Dr. Sidney Cohen, a psychiatrist then with the California Veterans Administration Hospital. According to Wilson, the session allowed him to re-experience a spontaneous spiritual experience he had had years before, which had enabled him to overcome his own alcoholism.
Heard is also responsible for introducing the then unknown Huston Smith to Huxley. Smith became one of the preeminent religious studies scholars in the United States. His book The World's Religions is a classic in the field, sold over two million copies and is considered a particularly useful introduction to comparative religion. The meeting with Huxley led eventually to Smith's connection to Timothy Leary.
In 1963, what some consider to be Heard's magnum opus, a book titled The Five Ages of Man, was published. According to Heard, the prevalent developmental stage among humans in today’s well-industrialized societies (especially in the West) is the fourth: the “total individual,” who is mentally dominated, feeling him- or herself to be autonomous, separate from other persons. In modern industrial societies, a person, especially if educated, has the opportunity to begin entering the “first maturity” of the humanic “total individual” in his or her mid teens. However, according to Heard -– based on his decades of studies, his intuition, and his many years of reflection –- a fifth stage is in the process of emerging: a post-individual psychological phase of persons and therefore of culture.
Heard termed this phase 'Leptoid Man' (from the Greek word lepsis: "to leap") because humans increasingly face the opportunity to 'take a leap' into a considerably expanded consciousness, in which the various aspects of the psyche will be integrated, without any aspects being repressed or seeming foreign. A society that recognizes this stage of development will honor and support individuals in a "second maturity" who wish to resolve their inner conflicts and dissolve their inner blockages and become the sages of the modern world. Further, instead of simply enjoying biological and psychological health, as Freud and other important psychiatric or psychological philosophers of the “total-individual” phase conceived, Leptoid man will not only have entered the “second maturity” of the complete individual but will become: a human of developed spirituality, similar to the mystics of the past; and a person of wisdom.
But we are still in the transitional phase, not really beyond the super-individualistic fourth, "humanic" phase. Heard's views were cautionary about developments in society that were not balanced, about inappropriate aims of our use of technological power. He wrote: "we are aware of our precarious imbalance: of our persistent and ever-increasing production of power and our inadequacy of purpose; of our critical analytic ability and our creative paucity; of our triumphantly efficient technical education and our ineffective, irrelevant education for values, for meaning, for the training of the will, the lifting of the heart, and the illumination of the mind.
Heard died on 14 August 1971 at his home in Santa Monica, California of the effects of several earlier strokes he had, beginning in 1966.