This introduction presents an overview of key concepts discussed in the subsequent chapters of this book. The book expresses the practice of analytical psychology as an experience. It deals with the idea of leaving out generalizations and abstractions, but this proved difficult and misleading. Originally a model became necessary for organizing and explaining data resulting from the application of a method, for example that used in abreaction therapy or psychoanalysis. The book emphasizes that from the point of view of psychotherapy the early period of achieving unit status is important for its conduct. Repression is evoked to explain one of a class of defences against parts of the whole person that are incompatible with others. In view of the extensive use of such methods, Jung thought that synchronicity might be an idea that could introduce another dimension of experience to the rational and scientific one dominating our civilization. The concept of individuation informs all psychotherapy conducted by analytical psychologists.