Believing that the use of primary sources is the best way of learning the thought system of a great thinker, I have decided to focus upon a single text of each of the psychotherapists considered in this book. Though the entire corpus of their work will be incorporated in this enquiry, our approach will be to critically consider a major text which established each one as a leading theorist in the field of psychotherapy. We will provide a biographical summary of each theorist followed by a textual analysis of a classic work in their repertoire. We will also include a comprehensive bibliography of each theorist relevant to each system of psychotherapy considered here. This work can be criticized for not incorporating all of each theorist’s writings but for two reason, that will not be done. First, their literary output makes that impracticable, and, second, a carefully considered treatment of one classic text seems preferable to a cursory glance at their entire literary corpus. Finally, we will consider the fundamentals of their thought in relationship to the practice of psychotherapy. Following the biographical sketch there will be an in-depth consideration of a primary text in the published repertoire of the psychotherapists being considered here. This author is convinced that nothing can substitute for acquaintance with the primary source of a thinker no matter how good the secondary source is for the reading of the original thinker must always trump the reading of one who has thought about the original thinker! Then and finally, we will explicate a few key concepts and theories for closer examination.