As is well known, the ancient sources supply only too little biographical information about Ptolemy to form a picture of the immediate context of his scientifical activity. The most remarkable reference is a passing observation by the 6th-century philosopher Olympiodorus in his commentary on Plato's Phaedo, providing both the length of his career and his workplace. The few scholars that have addressed the subject (Bullialdus, Halma, Letronne, Böll, Jones) have expressed quite different, and non-definitive views on both the reliability of Olympiodorus' account and on the geographical sense of the place he mentions.
I will propose here a reexamination of the whole problem based on the analysis of the various possible interpretations, which involves a close look at the Olympiodorus' passage, and at the evidence derived from Ptolemy's work, especially the so-called Canobic Inscription. This inscription plays an important role in this context, since it is mentioned by Olympiodorus, and its text as it has reached us through the manuscript tradition does also provide a geographical indication.
As a conclusion I would like to present speculative scenarios for Ptolemy's status as a scientist in second-century Alexandria.