R.N. Wilson's two-volume treatise on reflecting telescope optics has become a classic in its own right. It is intended to give a complete treatment of the subject, addressing the professional in research and industry as well as students of astronomy and amateur astronomers. This first volume, Basic Design Theory and its Historical Development, is devoted to the theory of reflecting telescope optics and systematically recounts the historical progress. The author's approach is morphological, with strong emphasis on the historical development. The book is richly illustrated including spot-diagrams analysing special systems in modern form. In this second edition, the historical section has been revised. Various improvements to the text have been made and new systems such as the 4-lens corrector of Delabre and the LADS corrector are now covered in this volume. The concluding part II treats Manufacture, Testing, Alignment, Modern Techniques.