Without attempting to argue for or against the merits of communism as an ideology: this is perhaps the definitive political call to arms in Western history, a fiery piece of writing that presents its ideas in an accessible way (bourgeoisie vs. proletariat is an easy-to-understand binary for the educated and uneducated alike). To have maintained its relevance into the 21st century is unheard of for a piece of political writing - that's a testament to something, whatever else you may say about it.