At the same time, Marx stressed that capitalism was unstable and prone to periodic crises. He suggested that over time capitalists would invest more and more in new technologies and less and less in labour. Since Marx believed that profit derived from surplus value appropriated from labour, he concluded that the rate of profit would fall as the economy grows. Marx believed that increasingly severe crises would punctuate this cycle of growth and collapse. Moreover, he believed that in the long-term, this process would enrich and empower the capitalist class and impoverish the proletariat. In section one of "The Communist Manifesto", Marx describes feudalism, capitalism and the role internal social contradictions play in the historical process: