Timothy Francis Leary was an American psychologist and writer known for his strong advocacy of psychedelic drugs. Evaluations of Leary are polarized, ranging from bold oracle to publicity hound. He was "a hero of American consciousness", according to Allen Ginsberg, and Tom Robbins called him a "brave neuronaut."
As a clinical psychologist at Harvard University, Leary worked on the Harvard Psilocybin Project from 1960 to 1962. He tested the therapeutic effects of lysergic acid diethylamide and psilocybin, which were still legal in the United States at the time, in the Concord Prison Experiment and the Marsh Chapel Experiment. The scientific legitimacy and ethics of his research were questioned by other Harvard faculty because he took psychedelics along with research subjects and pressured students to join in. However, the claims that Leary pressured unwilling students are refuted by at least one of Leary's students, Robert Thurman. Leary and his colleague, Richard Alpert, were fired from Harvard University in May 1963. Many people of the time only came to know of psychedelics after the Harvard scandal.
Leary believed that LSD showed potential for therapeutic use in psychiatry.