As with many medieval persons, his exact date of birth is not known. The first reference to him is found in a university document of the year 1328, in which he is mentioned as rector of the University of Paris. He might have died from the plague in 1358, but this is not certain either. In the thirty years between 1328 and 1358 he compiled textbooks on practically all subjects taught in Medieval Universities.
The basis of teaching in natural philosophy (which covered most of what we commonly call science) was formed by the books of Aristotle and the ancient, Arabic and medieval commentary's on those books. Most of Buridan's books are also commentaries on Aristotle's works. In these commentaries difficult issues were explained, conflicting theories treated, and own theories given. In many cases, these commentaries contained much original material and although they were commentaries on the works of Aristotle, they were often un-Aristotelian.
One of the most important books in natural philosophy was De Caelo. This book deals with the universe, the planets, and sublunar motion (the motion of heavy and light objects). Buridan wrote two types of commentaries on this book, an expositio and a set of questiones. The first type is a literal commentary, explaining, sentence for sentence, what Aristotle meant. The second type is a set of difficult problems and their solution. Problems treated include whether the universe is eternal, whether the planets are moved without friction, whether the earth is at rest in the center of the universe, what the cause is of the tides and many others.
The main topic of my thesis is a number of such questions from Buridan's questions on De Caelo. In these particular questions he investigates whether the heavens have a top, bottom, front, back, left and right. This is a strange topic to modern minds, but it is not so strange in the framework of Aristotelian philosophy. Aristotle considered the heaven to be alive and animated and for him the notion of front, back, left, right, top and bottom is intimedly connected with living beings. Only they have a top, bottom etc. strictly speaking, in all other things it is only a relative notion. In the middle ages the heaven was no longer considered alive and animated, and therefore many of Aristotle's explanations had to be revised. This process of adapting Aristotelian theories and modifying them to suit the medieval state of knowledge is an interesting research topic in my opinion.
A postscript version of my thesis is available. Comments are greatly welcomed. Someday I hope I'll be able to get parts of it published, but at the moment I spend too much time on chemistry.
Last modified: Aug 19, 1997
Peter Tieleman, tieleman@chem.rug.nl