In the mid-1960s, psychiatrist Stanislav Grof’s research in LSD psychotherapy challenged the orthodox Freudian model of mind. For years, Grof and his colleagues looked unsuccessfully for some kind of diagnostic system to predict the experiences of their clients in deep self-exploration. When Richard Tarnas applied archetypal astrology to this problem, Grof had to ironically concede that the one successful technique was even more controversial than his research in psychedelic therapy.