Throughout the period of training and in clinical practice, there is a tendency to develop a prejudiced view about ‘illicit’ or ‘illegal’ street drugs, including psychedelics. Many clinicians hold the simple view that cannabis exacerbates psychosis and heroin dependence is treated with substitute prescribing, and have little exposure to patients who misuse psychedelics. This in itself is a clue to understanding the essence of this book, namely that although psychedelic use is more prevalent than either cannabis or heroin use, this is not reflected in clinical practice, nor is it reflected in medical education.

In this well-researched and well-referenced book, the author has in a very logical manner explained that he is not arguing for the legalisation of psychedelic street drugs. Rather, he champions the cause of raising awareness and generating interest for further research into the medical use of psychedelics, predominantly as a tool to enhance psychotherapy interventions, but also drawing attention to their potential for treating other psychiatric conditions.

Dr Sessa’s reflections on how he became interested in psychedelic drug research make for an interesting read. He classifies and describes the effects of psychedelics in a mini-textbook fashion. His interest and expertise in this field are evident. What I found particularly fascinating was the hypothesis of how naturally occurring psychedelics may have influenced the evolution of culture and religion, and the author goes to great length in providing examples, through religious texts, of the use of these substances in the ancient world. He best sums it up when he concludes, ‘Psychiatry needs psychedelics, and psychedelics need psychiatry’. I couldn’t agree more.