I assume most of those who are reading this have noticed that while the Republicans accuse any Democrat who speaks on economic issues of class warfare, they have themselves been engaged in an aggressive policy of enriching the already rich at the expense of the poor. This has led me to think a bit about the history of philosophical discussions of the seemingly never ending class war.
One infrequently commented upon place in which the class war is discussed is in the writings of Nietzsche. Nietzsche is famous for presenting his contrast between what he called the master morality and the slave morality. They do end up roughly corresponding to morality as the rich would like the rules to be, and morality as the poor would like the rules to be. But Nietzsche hardly ever mentions money. His tendency to ignore money is a little bit odd, given what I'm sure some of his sources are.
I expect one of the primary sources of the great classical philologist's ideas has to have been Plato. In Republic, we see a sophisticated attack on the master morality. But Plato makes money central to his argument; the first spokesman for the moral theory Plato seeks to undermine, Cephalus, is notable almost exclusively for being wealthy. Further, the theory of Cephalus that money is equivalent to virtue is one of Plato's main targets. The argument Thrasymachus and eventually Glaucon and Adeimantus take up exploits the contradiction between the beliefs of Cephalus that being rich and being honest both are part of being good. It is evident to all that one can become richer by being dishonest under the right circumstances, so since being rich equals being good, Thrasymachus argues that we should really think it is dishonesty that makes us good.
Further, the emphasis on money is not just present in the first book and a half. More than two thousand years before Marx, Plato makes a very big deal of the importance of class struggle. He argues that his ideal republic will effortlessly win in a conflict with any Greek rival, because in every city in Greece apart from his ideal republic, there are really two cities. There are the rich and the poor, and they are ever ready to go to war with one another. So all the republic needs to do to have an overwhelming advantage over any rival city is to make an alliance with one of the perpetually warring factions against the other.
Plato, in what is perhaps an over-reaction, seems to try to resolve the contradiction between saying wealth is good and saying honesty is good by ditching both; his philosopher-kings are supposed to not care about wealth, but are also supposed to freely lie for the good of the state. However, the important point is that money is quite central to the discussion in Plato. Why does it not appear in Nietzsche?
The innocent explanation would be that wealth is only important to the extent that it is a source of power. Nietzsche certainly talks a lot about power, so it could be argued that he is simply concentrating on what is more fundamental.
However, there is another explanation, which reflects less well on Nietzsche. Recognizing the degree to which master morality is morality as the wealthy would have us see it would involve seeing that the master morality is quite widespread in modern times. While Nietzsche does not claim that the master morality has died out, he writes as if the slave morality were dominant in the modern era. Further, while he is not an enthusiast for the master morality, almost all of his most pointed criticisms are directed at the slave morality, perhaps for this very reason that he saw the slave morality as dominant. However, if the master morality is interpreted as morality according to the rich, it becomes apparent that it is still far more powerful than Nietzsche seems to have recognized. It is not clear why Nietzsche didn't recognize this, but it seems to stand as one of his larger mistakes.