The Communist Manifesto summarises Marx and Engels' theories concerning the nature of society and politics, namely that, in their own words, "[t]he history of all hitherto existing society is the history of class struggles". It also briefly features their ideas for how the capitalist society of the time would eventually be replaced by socialism. In the last paragraph of the Manifesto, the authors call for a "forcible overthrow of all existing social conditions", which served as a call for communist revolutions around the world.