All science would be superfluous if the outward appearance and the essence of things directly coincided.

Labor in the white skin can never free itself as long as labor in the black skin is branded.

The weapon of criticism can never replace the criticism of weapons.

...it happens that society is saved as often as the circle of its ruling class is narrowed, as often as a more exclusive interest asserts itself over the general. Every demand for the most simple bourgeois financial reform, for the most ordinary liberalism, for the most commonplace republicanism, for the flattest democracy is forthwith punished as an assault upon society and is branded as Socialism.

In this sense, the theory of the Communists may be summed up in the single sentence: Abolition of private property. - Manifesto of the Communist Party

Both for the production on a mass scale of this communist consciousness, and for the success of the cause itself, the alteration of men on a mass scale is necessary, an alteration which can only take place in a practical movement, a revolution; this revolution is necessary, therefore, not only because the ruling class cannot be overthrown in any other way, but also because the class overthrowing it can only in a revolution succeed in ridding itself of all the muck of ages and become fitted to found society anew.

Parliamentary cretinism: that peculiar malady which since 1848 has raged all over the Continent, which holds those infected by it fast in an imaginary world and robs them of all sense, all memory, all understanding of the rude external world.