Aulus Gellius’ Attic Nights, vol.iii, bk.XVI, XIII.p.177

1. Municipes and municipia are words which are readily spoken and in common use, and you would never find a man who uses them who does not think that he understands perfectly what he is saying.
But in fact it is something different, and the meaning is different.
2. For how rarely is one of us found who, coming from a colony of the Roman people, does not say what is far removed from reason and from truth, namely, that he is “municeps” and that his fellow citizens are “municeps”?
3 .So general is the ignorance of what “municipia” are and what rights they have, and how far they differ from a “colony”, as well as the belief that coloniae are better off than municipia.
4. With regard to the errors in this opinion which is so general the deified Hadrian, in the speech which he delivered in the senate “In behalf of the Italicenses”, (De Italicensibus. Italica was a city in Spain on the river Baetis, opposite Hispalis (Seville). It was founded by Scipio Africanus maior and peopled by his veterans; whence the name “the Italian city”.) from whom he himself came, discoursed most learnedly, showing his surprise that the municipia, among whom he names the citizens of Utica, when they might enjoy there own customs and laws, desired instead to have the rights of colonies.
5. Moreover, he asserts that the citizens of Praeneste earnestly begged and prayed the emperor Tiberius that they might be changed from a colony into the condition of a municipium, and that Tiberius granted there request by way of conferring a favour, because in there territory, and near their town itself, he had recovered from a dangerous illness.
6. ”Municipes”, then, are Roman citizens from free towns, using their own laws and enjoying their own rights, merely sharing with the Roman people an honorary munus, or “privilege”- from the enjoyment of which privilege they appear to derive there name-, and bound by no other compulsion and no other law of the Roman people, except such as their own citizens have officially ratified.
7. We learn besides that the people of Caere were the first municipes without the right of suffrage, and that it was allowed them to assume the honour of Roman citizenship, but yet to be free from service and burdens, in return for receiving and guarding sacred objects during the war with the Gauls. Hence by contraries those tablets were called Caerites on which the censors ordered those to be enrolled whom they deprived of their votes by way of disgrace.
8. But the relationship of the “colonies” is a different one; for they do not come into citizenship from without, nor grow from roots of their own, but they are as it were transplanted from the State and have all the laws and institutions of the Roman people, not those of their own choice. 9. This condition, although it is more exposed to control and less free, is nevertheless thought preferable and superior because of the greatness and majesty of the Roman people, of which those colonies seem to be miniatures, as it were, and in a way copies; (their government was modelled on that of Rome, with a senate (decuriones), two chief magistrates (ii viri iure dicundo), elected annually, etc.) and at the same time because the rights of the municipal towns became obscure and invalid, and from ignorance of their existence the townsmen are no longer able to make use of them.