  There are exactly three more or less solid facts on the basis of which one can reconstruct the general parameters of Olympiodorus’ life. First, he held the chair of philosophy in Alexandria (the majority of manuscripts of his work refer to him as “the philosopher of Alexandria”). Second, he saw himself as intellectual heir to Ammonius (see in Meteor. 153,7; 175,14; 188,36; 238,19; 255,23; 256,27; Olympiodorus refers to Ammonius frequently as “the great philosopher”, in one case as “our philosopher”, in Gorg.  §40.5; cf. §39.2, and he may have been Ammonius’ pupil).  Third, some of his lectures were delivered not long after 565 (cf.  in Meteor. 52,31; the way Olympiodorus reminds his students about a comet that had appeared in March/April 565 suggests that the event occurred a couple of years earlier). It is generally assumed that Ammonius passed away (or at least stopped teaching) sometime in the period between 517 and 526. If these dates are correct, we can infer that Olympiodorus was a young man when he came to be one of the last pupils of Ammonius and that he led an active intellectual life into his late sixties, or early seventies of that century. Accordingly, the dates of Olympiodorus’ life should be approximately 500–570, encompassing the entire reign of emperor Justinian the Great (527–565). Since John Philoponus was teaching philosophy actively until the mid-30s (without ever holding the chair of philosophy), it seems likely that Olympiodorus began his teaching career around that time to become the official successor to Ammonius.