" We saw this contradiction in action in Marx's analysis of struggles over the length of the working day. Individual capitalists, we there discovered, each of them acting in his or her own self-interest and locked in competitive struggle with each other, can produce an aggregative result which goes against their class interest seen as a whole. By their individual action they can endanger the basis for accumulation. And since accumulation is the means whereby the capitalist class reproduces itself, they can endanger the basis for their own reproduction. They are then forced to constitute themselves as a class — usually through the agency of the state — and to put limits upon their own competition. But in so doing they are forced to intervene in the exchange process — in this instance in the labour market -- and thereby to offend the rules of individuality and freedom in exchange. "

― David Harvey , The Limits to Capital