In late 1847, Marx and Engels began writing what was to become their most famous work – a programme of action for the Communist League. Written jointly by Marx and Engels from December 1847 to January 1848, "The Communist Manifesto" was first published on 21 February 1848. "The Communist Manifesto" laid out the beliefs of the new Communist League. No longer a secret society, the Communist League wanted to make aims and intentions clear to the general public rather than hiding its beliefs as the League of the Just had been doing. The opening lines of the pamphlet set forth the principal basis of Marxism: "The history of all hitherto existing society is the history of class struggles". It goes on to examine the antagonisms that Marx claimed were arising in the clashes of interest between the bourgeoisie (the wealthy capitalist class) and the proletariat (the industrial working class). Proceeding on from this, the "Manifesto" presents the argument for why the Communist League, as opposed to other socialist and liberal political parties and groups at the time, was truly acting in the interests of the proletariat to overthrow capitalist society and to replace it with socialism.