and early 1970s, Leary formulated his eight-circuit model of consciousness in collaboration with writer Brian Barritt. The essay "The Seven Tongues of God" claimed that human brains have seven circuits producing seven levels of consciousness. An eighth circuit was added in the 1973 pamphlet Neurologic, written with Joanna Leary while he was in prison. This eighth-circuit idea was not exhaustively formulated until the publication of Exo-Psychology by Leary and Robert Anton Wilson's Cosmic Trigger in 1977. Wilson contributed to the model after befriending Leary in the early 1970s, and used it as a framework for further exposition in his book Prometheus Rising, among other works. Leary believed that the first four of these circuits ("the Larval Circuits" or "Terrestrial Circuits") are naturally accessed by most people at transition points in life such as puberty. The second four circuits ("the Stellar Circuits" or "Extra-Terrestrial Circuits"), Leary wrote, were "evolutionary offshoots" of the first four that would be triggered at transition points as humans evolve further. These circuits, according to Leary, would equip humans to live in space and expand consciousness for further scientific and social progress. Leary suggested that some people might trigger these circuits sooner through meditation, yoga, or psychedelic drugs specific to each circuit. He suggested that the feelings of floating and uninhibited motion sometimes experienced with marijuana demonstrated the purpose of the higher four circuits. The function of the fifth circuit was to accustom humans to life at a zero gravity environment. Leary did not specify the location of the eight circuits in any brain structures, neural organization, or chemical pathways. He wrote that a higher intelligence "located in interstellar nuclear-gravitational-quantum structures" gave humans the eight circuits. A "U.F.O. message" was encoded in human DNA. Many researchers believed that Leary provided little scientific evidence for his claims. Even before he began working on psychedelics, he was known as a theoretician rather than a data collector. His most ambitious pre-psychedelic work was Interpersonal Diagnosis Of Personality. The reviewer for The British Medical Journal, H. J. Eysenck, wrote that Leary created a confusing and overly broad rubric for testing psychiatric conditions. "Perhaps the worst failing of the book is the omission of any kind of proof for the validity and reliability of the diagnostic system," Eysenck wrote. "It is simply not enough to say" that the accuracy of the system "can be checked by the reader" in clinical practice. In