An investigation of the ways in which science has a bearing on the clinical techniques and practice of psychotherapy. Robert Langs notes striking parallels between the emotion-processing mind and phenomena that have been scientifically observed and charted in the areas of evolution, the immune system and the brain. He argues that theoretical and clinical efforts should be focused on understanding the deep, evolved factors behind human behaviour such as suffering, deception, self-limitations, and death anxieties. This approach to the quest for better psychotherapeutic knowledge shows how a scientific foundation for psychotherapy is both necessary and possible.