Democracy for Aristotle

I find it amazing that for over 2000 years there has been some form of democracy on this earth. In his essay on democracy, Aristotle talks about the three elements in a state, "the very rich, the very poor, and the mean". This is directly related to our upper class, lower class and our middle class in America. He goes on about how the middle class needs to be largest to keep the other two classes in check and keep either of them from completely taking over a community. By far, in America the largest class is the middle class and they are constantly trying to keep the upper class from having absolute control over all monies, and keeping the lower class from sucking them dry by those that "use the system" to live. It seems to me though, that in Greek civilization there wasn't really a middle class at all. There were the citizens, all male, who held the political positions, decided everything and had money and then there was everyone else, women, children and slaves, who basically no rights and not much money. Maybe this is why democracy fell apart so fast in Athens.