Why did Marx and Engels form a partnership in Paris?

Karl Marx and Friedrich Engels formed their historic partnership in Paris following a 10-day visit by Engels to Marx in 1844. Having previously met in Cologne, the two men reconnected in Paris, which was then a major center for socialist thought and various communist sects.123

Their partnership was driven by a shared conviction that European society could not be reformed from within and required a fundamental transformation. Both men were deeply disturbed by the systemic injustices of a society divided by class, particularly the poverty and squalor faced by the industrial working class, or proletariat.2

During this period, they discovered that they held remarkably similar views on the nature of capitalism and the necessity of replacing it with communism. This meeting established a lifelong collaboration in which they combined their intellectual resources to promote the socialist movement, eventually leading to the development of their materialist conception of history and the drafting of the Communist Manifesto.241