Over the past 150 years, capitalism has repeatedly fallen into deep crises, regularly devastating the lives working class and poor people and prompting social and political upheavals. Writing in the nineteenth century, Marx explained why contradictions within capitalism left the global economy prone to cyclical busts and long-term weaknesses. But he did not offer a singular theory of crisis in any one place, instead, his writing on the topic is scattered in different writings and in notes. This has led to many debates among socialists about how to explain why capitalism falls into crises, and how to apply Marx's theories to assess the current economic situation.