'As the problems raised in this book are fundamental to learning they have a long history of investigation and discussion. In phsycho-analytical practice, particularly with patients displaying symptoms of disorders of thought, it becomes clear that psycho-analysis has added a dimension to problems if not to their solution. 'This book deals with emotional experiences that are directly related both to theories of knowledge and to clinical psycho-analysis, and that in the most practical manner. '- Wilfred R. Bion, from the Introduction