Book excerpt: In this classic text, Joseph Harris traces the evolution of college writing instruction since the Dartmouth Seminar of 1966. A Teaching Subject offers a brilliant interpretive history of the first decades during which writing studies came to be imagined as a discipline separable from its partners in English studies. Postscripts to each chapter in this new edition bring the history of composition up to the present. Reviewing the development of the field through five key ideas, Harris unfolds a set of issues and tensions that continue to shape the teaching of writing today. Ultimately, he builds a case, now deeply influential in its own right, that composition defines itself through its interest and investment in the literacy work that students and teachers do together. Unique among English studies fields, composition is, Harris contends, a teaching subject.