Dr. Timothy Francis Leary (October 22, 1920 - May 31, 1996) was a highly influential American psychologist and writer, known in later life for advocating advanced research into the therapeutic benefits of psychedelic drugs. A controversial figure during the 1960s and 1970s, he defended the use of the drug LSD for its therapeutic, emotional and spiritual benefits, and even believed it showed incredible potential in the field of psychiatry. Leary also popularized the phrase "Turn on, tune in, drop out." Both proved to be hugely influential on the 1960s counterculture. Largely due to his influence in this field, he was attacked by conservative figures in the United States, and described as "the most dangerous man in America" by President Richard Nixon.