The historian Agathias (Hist. II 30.3-31.4) relates that under the Emperor Justinian seven philosophers (Damascius, Simplicius, Eulamius, Priscianus, Hermeias, Diogenes, and Isidorus) sought refuge in Persia because of their own country's anti-pagan laws but that they ultimately returned in 532 to the Roman Empire. There have been many hypotheses about the fate of these philosophers after their return. Most recently M. Tardieu has argued that these philosophers went to Harran, a town that was located on the Persian frontier and that remained mostly pagan until the tenth century. This hypothesis, which M. Tardieu had backed with a number of arguments, has found many echoes, both positive and negative, in subsequent secondary literature. Yet the complexity of the issue has never really been faced by Tardieu's critics. For example, the fact that, according to Arab sources, Simplicius could found a famous school of mathematics has been completely neglected, as has the fact that details of the dogmas of Manicheanism, which he obtained through his encounter with a member of that sect, enable one to envision a Mesopotamian locale for this encounter. The present study aims at taking stock of the elements of this controversy, beginning with a detailed article by D. Watts and a review by C. Luna. Watts mostly bases his criticisms of M. Tardieu and me on Luna's summary. In the conclusion (pages 58-59), I summarize the main points that seem to me to confirm M. Tardieu's hypothesis.