Updated

The New York Public Library announced Thursday that it has acquired the papers of LSD guru Timothy Leary, who coined the phrase "turn on, tune in, drop out."

The 335 boxes of papers, videotapes, photographs and other Leary artifacts will provide scholars with access to one of the most influential figures of the 20th century, library officials said.

"Leary's papers are an unparalleled resource for researchers studying the emergence and development of the American counterculture," manuscript curator William Stingone said.

Leary was a Harvard psychology lecturer who became notorious for advocating the therapeutic use of psychedelic drugs including LSD and psilocybin mushrooms. President Richard Nixon called Leary "the most dangerous man in America." Leary spent several years in prison and in exile abroad in the 1970s. He died in 1996.

Denis Berry, a trustee of the Leary estate, told The New York Times that the library paid $900,000 for the collection, some of which is being donated back to finance the processing of the material. The rest will pay the estate's caretakers and then be divided among Leary's surviving children and grandchildren.

The collection includes thousands letters from figures such as Allen Ginsberg, Ken Kesey, G. Gordon Liddy and Cary Grant.

There are also hundreds of reports documenting the psilocybin-induced experiences of Harvard graduate students and others.

The collection will be available to researchers and the public in about two years after the papers have been processed.