Deliberate provocation of mystical experience, particularly by LSD and related hallucinogens, in contrast to spontaneous visionary experiences, entails dangers that must not be underestimated. Practitioners must take into account the peculiar effects of these substances, namely their ability to influence our consciousness, the innermost essence of our being. The history of LSD to date amply demonstrates the catastrophic consequences that can ensue when its profound effect is misjudged and the substance is mistaken for a pleasure drug. Special internal and external advance preparations are required; with them, an LSD experiment can become a meaningful experience. Wrong and inappropriate use has caused LSD to become my problem child.

Foreword. - LSD : My Problem Child (1980)