Religious suffering is, at one and the same time, the expression of real suffering and a protest against real suffering. Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions. It is the opium of the people.

Karl Marx, Introduction to A Contribution to the Critique of Hegel’s Philosophy of Right (1843)



Private property has made us so stupid and one-sided that an object is only ours when we have it – when it exists for us as capital, or when it is directly possessed, eaten, drunk, worn, inhabited, etc., – in short, when it is used by us. Although private property itself again conceives all these direct realisations of possession only as means of life, and the life which they serve as means is the life of private property – labour and conversion into capital.

Karl Marx, Private Property and Communism (1844)



The philosophers have only interpreted the world, in various ways; the point, however, is to change it.

Karl Marx, Theses On Feuerbach (1845)



As individuals express their life, so they are. What they are, therefore, coincides with their production, both with what they produce and with how they produce. The nature of individuals thus depends on the material conditions determining their production.

Karl Marx, The German Ideology (1845)



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.

Karl Marx, The German Ideology (1845)



The slave frees himself when, of all the relations of private property, he abolishes only the relation of slavery and thereby becomes a proletarian; the proletarian can free himself only by abolishing private property in general.

Frederick Engels, The Principles of Communism (1847)



What the bourgeoisie therefore produces, above all, are its own grave-diggers. Its fall and the victory of the proletariat are equally inevitable.

Karl Marx and Frederick Engels, Manifesto of the Communist Party (1848)



We by no means intend to abolish this personal appropriation of the products of labour, an appropriation that is made for the maintenance and reproduction of human life, and that leaves no surplus wherewith to command the labour of others. All that we want to do away with is the miserable character of this appropriation, under which the labourer lives merely to increase capital, and is allowed to live only in so far as the interest of the ruling class requires it.

Karl Marx and Frederick Engels, Manifesto of the Communist Party (1848)



The mode of production of material life conditions the social, political and intellectual life process in general. It is not the consciousness of men that determines their being, but, on the contrary, their social being that determines their consciousness.

Karl Marx, Preface of A Contribution to the Critique of Political Economy (1859)



The capitalist mode of production and accumulation, and therefore capitalist private property, have for their fundamental condition the annihilation of self-earned private property; in other words, the expropriation of the laborer.

Karl Marx, Capital: Volume 1, Chapter 33: The Modern Theory of Colonisation (1867)



The political freedoms, the right of assembly and association, and the freedom of the press – those are our weapons. Are we to sit back and abstain while somebody tries to rob us of them? It is said that a political act on our part implies that we accept the exiting state of affairs. On the contrary, so long as this state of affairs offers us the means of protesting against it, our use of these means does not signify that we recognise the prevailing order.

Frederick Engels, Apropos Of Working-Class Political Action (1871)



Every step of real movement is more important than a dozen programmes.

Karl Marx, Letter to Bracke (In Brunswick) (1875)



Labour is the source of all wealth, the political economists assert. And it really is the source Ð next to nature, which supplies it with the material that it converts into wealth. But it is even infinitely more than this. It is the prime basic condition for all human existence, and this to such an extent that, in a sense, we have to say that labour created man himself.

Frederick Engels, The Part played by Labour in the Transition from Ape to Man (1876)



We...reject every attempt to impose on us any moral dogma whatsoever as an eternal, ultimate and forever immutable ethical law on the pretext that the moral world, too, has its permanent principles which stand above history and the differences between nations. We maintain on the contrary that all moral theories have been hitherto the product, in the last analysis, of the economic conditions of society obtaining at the time. And as society has hitherto moved in class antagonisms, morality has always been class morality; it has either justified the domination and the interests of the ruling class, or ever since the oppressed class became powerful enough, it has represented its indignation against this domination and the future interests of the oppressed. That in this process there has on the whole been progress in morality, as in all other branches of human knowledge, no one will doubt. But we have not yet passed beyond class morality.

Frederick Engels, Anti-Dühring (1877)



The proletariat seizes the public power, and by means of this transforms the socialized means of production, slipping from the hands of the bourgeoisie, into public property. By this act, the proletariat frees the means of production from the character of capital they have thus far borne, and gives their socialized character complete freedom to work itself out. Socialized production upon a predetermined plan becomes henceforth possible. The development of production makes the existence of different classes of society thenceforth an anachronism. In proportion as anarchy in social production vanishes, the political authority of the State dies out. Man, at last the master of his own form of social organization, becomes at the same time the lord over Nature, his own master – free.
To accomplish this act of universal emancipation is the historical mission of the modern proletariat. To thoroughly comprehend the historical conditions and this the very nature of this act, to impart to the now oppressed proletarian class a full knowledge of the conditions and of the meaning of the momentous act it is called upon to accomplish, this is the task of the theoretical expression of the proletarian movement, scientific Socialism.

Frederick Engels, Socialism: Utopian and Scientific (1880)



The revolutionary power which will socialise the instruments of labour taken from the capitalist class, will have to mount guard over the general interests of society served by the socialised industries, and in particular over the interests of those directly engaged in them.

Paul Lafargue, Socialism and Nationalisation (1882)



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

Karl Marx, Capital Vol. III Chapter 48 (1883)



We must not be like some Christians who sin for six days and go to church on the seventh, but we must speak for the cause daily, and make the men, and especially the women that we meet, come into the ranks to help us.

Eleanor Marx, Speech on the First May Day (1890)



The division of society into a small, excessively rich class and a large, propertyless