This is Grof's first of many, many books on related subjects, and it precedes the period of time when he began to develop his holotropic breathwork techniques. In this work, he attempts to report on the preliminary findings and interpretations from his years of extensive psychiatric research involving LSD-25 at the Prague Psychiatric Research Center. In many ways, the model which he developed from this work has a consistency and a clarity which diminishes with the elaboration of the complexity of his later discoveries. Don't get me wrong. The complexity that he realizes in the further refinement of his model is appropriate--its just that the results of LSD research are more unambiguous and less complex than the "therapeutic" experiences that emerge from non-drug sessions of any sort, whether brought on by a close encounter with death, spiritual practices, or spontaneous emergence. In many ways, the LSD research exposes with great clarity the mechanisms which underlie the mysterious phenomena of "transformation". This is somewhat natural and obvious. However, across the spectrum of what Grof calls--non ordinary states--we are dealing with the amplification of mental processes. LSD is like turning the amplifier up to 11, right away. Other methods of mental amplification are more gradual, and take greater time and effort. Therefore, even though the end results may often be just as dramatic--the theoretical interpretations can be more ambiguous and require greater sensitivity to nuance. The complexity of psychological factors are more difficult to sort out. Somehow, these distinctions find their way into the presentations in Grof's books, and consequently, I think the later works are more difficult for newcomers to grasp. This book is fairly straightforward, and direct, and consequently is a good introduction to Grof's thinking, and its evolution.