In studying the literature connected with my work, I became aware of the great universal significance of visionary experience. It plays a dominant role, not only in mysticism and the history of religion, but also in the creative process in art, literature, and science. More recent investigations have shown that many persons also have visionary experiences in daily life, though most of us fail to recognize their meaning and value. Mystical experiences, like those that marked my childhood, are apparently far from rare.

Foreword. - LSD : My Problem Child (1980)