“Nor will we explain to them [our wise philosophers] that it is only possible to achieve real liberation in the real world and by employing real means, that slavery cannot be abolished without the steam engine and the mule and the spinning-jenny, serfdom cannot be abolished without improved agriculture, and that, in general, people cannot be liberated as long as they are unable to obtain food and drink, housing and clothing in adequate quality and quantity. ‘Liberation’ is an historical and not a mental act, and it is brought about by historical conditions, the development of industry, commerce, agriculture, the conditions of intercourse…”
– Karl Marx, “The German Ideology”