"An ounce of action is worth a ton of theory."

"Just as Darwin discovered the law of evolution in organic nature, so Marx discovered the law of evolution in human history; he discovered the simple fact, hitherto concealed by an overgrowth of idealogy [sic], that mankind must first of all eat and drink, have shelter and clothing, before it can pursue politics, science, religion, art etc."

"Thus at every step we are reminded that we by no means rule over nature like a conqueror over a foreign people, like someone standing outside nature - but that we, with flesh, blood and brain, belong to nature, and exist in its midst, and that all our mastery of it consists in the fact that we have the advantage over all other creatures of being able to learn its laws and apply them correctly."

"Ideas often kindle each other, like electrical sparks."

"...it was always our view that in order to attain this [proletarian revolution] and the other far more important aims of the future social revolution, the working class must first take possession of the organised political power of the state and by its aid crush the resistance of the capitalist class and organise society anew."

"A revolution is certainly the most authoritarian thing there is; it is the act whereby one part of the population imposes its will upon the other part by means of rifles, bayonets and cannon - authoritarian means, if such there be at all; and if the victorious party does not want to have fought in vain, it must maintain this rule by means of the terror which its arms inspire..."

"The proletarians, driven to despair, will seize the torch which Stephens has preached to them; the vengeance of the people will come down with a wrath of which the rage of 1795 gives no true idea. The war of the poor against the rich will be the bloodiest ever waged."

"All the other large and small nationalities and peoples are destined to perish before long in the revolutionary world storm... The next world war will result in the disappearance from the face of the earth not only of reactionary classes and dynasties, but also of entire reactionary peoples. And that, too, is a step forward."

"One day we shall certainly 'reduce' thought experimentally to molecular and chemical motions in the brain; but does that exhaust the essence of thought?"