The chapter on Communes and the Third Estate gives a rather surprising (to me) explanation for the origin of the Communes. These begin as a response to Feudalism, so Feudalism needs to be understood first. After the Germanic invasion, there was no central government and petty nobles gradually took control of lands that extended about as far as you could see from the top of your house. That is, there were countless little zones of several square miles ruled by a lord, protected by knights, and these would enslave and tax the serfs. Since squabbles between the petty lords were endless, so was the need for taxation. For towns, we generally had the same situation, except that the petty noble was usually tied in with the bishop, unless the bishop was the petty noble.
When the peasantry revolted and deposed the petty noble, or perhaps executed the bishop and burned his property, there would be a brief time of self governance. This was a commune. The problem was that the sort of uncivilized barbarity that characterized the bishops and nobles and which prompted the peasants to revolt was fairly common among the peasants also, so the usual consequence of the throwing off of the bishops and nobles was an explosion of crime and violence by your neighbors. Eventually the peasants would be compelled to seek a strong lord to bring back order. As Guizot put it, there was an inevitable conflict between freedom and security, so that it was impossible to have both at the same time. The communes were thus never stable, since anarchy, the central government, and the nearby nobles all conspired against them. Yet they did spring up here and there over much of France until the central government succeeded in weakening the feudal system. To the north in Flanders, the economy flourished on trade and crafts, so that the system of communes was much more durable.