Marxism is a revolutionary worldview that must always struggle for new revelations.

The clergy, no less than the capitalist class, lives on the backs of the people, profits from the degradation, the ignorance and the oppression of the people.

Only through the conscious action of the working masses in city and country can it be brought to life, only through the people's highest intellectual maturity and inexhaustible idealism can it be brought safely through all storms and find its way to port.

[Geology] opens up such wide intellectual vistas and supplies a more perfectly unified and more comprehensive conception of nature than any other science.

History is the only true teacher, the revolution the best school for the proletariat.

The more that social democracy develops, grows, and becomes stronger, the more the enlightened masses of workers will take their own destinies, the leadership of their movement, and the determination of its direction into their own hands.

Only to the rude ear of one who is quite indifferent does the song of a bird seem always the same.