During my research on university teaching and disputation techniques I encountered several times the philosopher John of Jandun. I quoted some of his disputed questions and was intrigued by the way in which he expressed himself, in a personal style, confident and openminded at the same time. Thus, after finishing what I could contribute to the study of disputation, I decided to explore the works of this early fourteenth-century scholar in order to discover, as far as possible, the person behind the writings and, as far as possible, the character of his teaching at the arts faculty.

My initial intention was to read, at least partly, all his works, but I soon discovered that it would take me another lifetime to achieve a more or less satisfying account of my findings. Consequently, I decided to limit my efforts for the moment to only one literary genre, to my eyes the most important one for the understanding of Jandun’s teaching: the commentaries.

Several younger colleagues, especially Jean-Baptiste Brenet and Iacopo Costa, have started a research programme around John of Jandun, which will comprise critical editions of his writings. This will be a precious contribution to the understanding of this important master. My own documentation consists in manuscripts and early editions, but in some cases I will refer to forthcoming editions instead of giving tentative transcriptions.

Two fundamental studies have been published in the last century by MacClintock and Schmugge; I will of course constantly refer to them. Both have tried to establish the chronological order of John’s writings, a difficult task as long as all the works have not benefitted of a critical edition. However, for the commentaries this is less problematic and I will present a list in what I think is the most probable chronological order.

My main objective in the following pages is to describe the character of the commentaries and their relation to John’s actual teaching. Thus, once again I concentrate on intellectual history, and not on philosophical doctrine. For this purpose I rely on the transcription of selected passages. The study of the various prologues, treated in Appendix I, will contribute to a wider view of John’s ideas on the subject and its place in the field of philosophy.

Several friends and colleagues, among whom Joël Biard and Sten Ebbesen, helped me with specific or more general problems. I would like to express my thanks to all of them. In particular, I want to mention Michele Meroni, who took the difficult and important task of identifying the sources quoted in the passages of the commentaries very conscientiously, sometimes digging deep into the possible origin of the quotations. Bill Courtenay kindly answered my questions on institutional points and then accepted to read the Introduction, offering very helpful suggestions.

Also, Paola Bernardini read and commented on the various chapters and the introduction. Her insights and criticism helped me to finish this study, and encouraged me to think that any publication was better than no publication.

Indeed, I quite understand that the way in which I present this work falls far short of the academic rules, which I followed in my earlier publications. Still, I trust that it will be useful for scholars and students interested in John of Jandun. Thus, I decided to add it as part of my website and I am grateful to Félix Medioni for the way in which he transformed my typescript into an esthetical follow up to my earlier web publications.