The Communist Manifesto (Unabridged‪)‬

The Communist Manifesto summarizes Marx and Engels' theories concerning the nature of society and politics. They believe, "The 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. Near the end of the manifesto, the authors call for "forcible overthrow of all existing social conditions," which served as the justification for all communist revolutions around the world.