Who was Timothy Leary? Prophet? Charlatan? Mystic? Mephisto? Years after his death his legacy is still contested, with advocates and detractors both passionately debating his worth. The Pied Piper of LSD, the man who coined the phrase "turn on, tune in, drop out," eulogized in song, his image disseminated on posters, Leary was perhaps the most famous academic of the 1960s, ranking with Marshall McLuhan as prophet of the post-industrial age. He began the decade as a Harvard professor and ended it in prison. During his life he was a clinical psychologist doing groundbreaking work in behavioral change, but he became a rebel, a guru, a fugitive, and a prisoner. Leary's life never lacked for adventure, nor his work for controversy, but to this day it remains unclear whether drugs were his salvation or his ruin.

Born to an alcoholic Army dentist and a...