This book has had a long gestation. I started chronicling China's Cultural Revolution (1966–1976) while it was taking place, for a variety of mainly British newspapers, magazines, and scholarly journals as well as BBC TV and Radio. In 1968, I began researching the origins of this political convulsion. Three decades later I published the last volume in what had turned into a trilogy on the subject. In the meanwhile I had joined the Harvard faculty, and shortly after I arrived there, in the mid-1980s, a very distinguished historian asked me to give a course on the Cultural Revolution in a section of Harvard College's Core Program called Historical Study B. The formal remit of this section is to "focus closely on the documented details of some central historical event or transformation … sufficiently delimited in time to allow concentrated study of primary source materials." My colleague explained that the assumption was that all the documentation was in and all emotion had been spent, thus providing the possibility of greater objectivity. I explained that very few reliable primary materials were available, and that in China, and even among some Western China scholars, emotions still ran deep over the events of the tumultuous Cultural Revolution decade. However, by this time I had taken on the co-editorship with John K. Fairbank of the final two volumes of the Cambridge History of China, covering the People's Republic of China, and had undertaken to write a chapter covering most of the Cultural Revolution period, and eventually I decided I might as well teach the course anyway. The course was unexpectedly popular and required a sourcebook of readings for the students. Preparing it, I found that most of the English-language materials had been written in the 1970s and early 1980s, mainly on the basis of the materials issued during the Cultural Revolution by Mao and his victorious leftist coalition. Significant materials were finally beginning to emerge in Chinese to permit presentation of a more balanced picture of events, steering between the Scylla of the Maoist radicals and the Charybdis of the Deng-era survivors.