  Autrecourt wrote nine letters to Bernard of Arezzo, only two of which survive. In addition, there is one letter from master Giles addressed to Autrecourt, along with a brief response by the latter, which, however, breaks off in mid-sentence. The correspondence has been preserved in two manuscript copies from the intellectual milieu of the Collège de Sorbonne. Together the letters form a small dossier, the central item of which is the letter from Master Giles. Apparently, the only reason the two letters to Bernard were copied was because they are mentioned in the letter from Master Giles. The correspondence between Autrecourt and Bernard of Arezzo is much earlier, dating from the time when both were theology students, engaged as opponents in each other’s Principia, i.e., inaugural lecture on the Sentences. They can be dated between October 1335 and June 1336, although both Principia are now lost. There is no evidence that Autrecourt ever actually wrote a commentary on the Sentences, which, in any case was not a formal requirement for obtaining a degree. The theme of the discussion in the Principia and the letters to Bernard of Arezzo is the validity of Aristotle’s principle of non-contradiction, as presented in Book IV of the Metaphysics.