In externals Alexandria was every inch a city. It had the high walls, which, as Alcaeus tells us, do _not_ constitute a state. It had the tribe and deme, or district division, and it had its various grades of citizens, determined by the duties and imposts to which they were subjected. Of its tribe and district division we know some details. There were probably five tribes, each of which consisted of twelve demes, or districts, which in turn had twelve phratries, or wards. The tribes were known by the first five letters of the Greek alphabet. In the absence of even formal political rights, this division can have been made simply in the interests of the census and the police. The obligations to pay taxes and perform military service were very real ones, and their proper enforcement necessitated some such organization of the city.[105] Different classes of citizenship were at once created by the establishment of special taxes and special exemptions. The peculiar Greek fiscal arrangement known as the liturgy, which made the performance of certain services to the state a means of compounding for taxes, was also in vogue. We have records of certain of these classes of citizens, or inhabitants, and it is at least probable that there were other classes of which we know nothing. First of all, there were the Macedones, or Macedonians. These form a specially privileged group, whose residence was probably by no means confined to Alexandria. Just what their privileges were we do not know, but that they lay chiefly in fiscal exemptions of one sort or another, is almost certain. Then there were the Alexandreis, or Alexandrians. We know that there were at least two groups—those that were enrolled in a given tribe, or deme, and those not so enrolled. We can only conjecture the purpose of this division, and one conjecture will be mentioned later. Besides these, there were other men whose legal right to residence was unquestioned. They were variously designated. We find Persians, Jews, and other nationalities, qualified with the phrase τῆς ἐπιγονῆς, which means literally “of the descent,” but the exact force of which is unknown. This classification procured for those so termed certain very much valued exemptions. Native Egyptians also were present, paying a special poll-tax, and no doubt a very large number of metics and transient foreigners. Greek publicists regarded the presence of a large number of metics and foreign merchants as a sign of great prosperity.[106] We may be sure that no burdensome restrictions made the settling of these classes difficult at Alexandria.