xy

Remarks against personality cults from a letter to W. Blos (10 November 1877).
Context: Neither of us cares a straw for popularity. A proof of this is for example, that, because of aversion to any personality cult, I have never permitted the numerous expressions of appreciation from various countries with which I was pestered during the existence of the International to reach the realm of publicity, and have never answered them, except occasionally by a rebuke. When Engels and I first joined the secret Communist Society we made it a condition that everything tending to encourage superstitious belief in authority was to be removed from the statutes.

Early Writings, translated and ed. by , p. 159. https://www.marxists.org/archive/marx/works/1844/epm/3rd.htm <br class="br">Context: 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 we directly possess, eat, drink, wear, inhabit it, etc., in short, when we use it. Although private property conceives all these immediate realizations of possession only as means of life; and the life they serve is the life of private property, labor, and capitalization. Therefore all the physical and intellectual senses have been replaced by the simple estrangement of all these senses – the sense of having. So that it might give birth to its inner wealth, human nature had to be reduced to this absolute poverty.

Die Philosophen haben die Welt nur verschieden interpretirt; es kommt aber darauf an, sie zu verändern.
http://books.google.com/books?id=xyc9AAAAYAAJ&q=%22Die+Philosophen+haben+die+Welt+nur+verschieden%22+%22es+kommt+aber+darauf+an+sie+zu+ver%C3%A4ndern%22&pg=PA72#v=onepage
"Theses on Feuerbach" (1845), Thesis 11, Marx Engels Selected Works,(MESW), Volume I, p. 15; these words are also engraved upon his grave.
First published as an appendix to the pamphlet Ludwig Feuerbach and the End of Classical German Philosophy by Friedrich Engels (1886)
Source: Eleven Theses on Feuerbach

Actually from State and Revolution by Vladimir Lenin, paraphrasing Marx in The Civil War in France.
Misattributed

Source: The German Ideology (1845/46), International Publishers, ed. Chris Arthur, p. 103.

Private Property and Communism, p. 43.
Paris Manuscripts (1844)

Source: Economic and Philosophic Manuscripts of 1844

Vol. I, Part 4.
The German Ideology (1845/46)
Context: Communism differs from all previous movements in that it overturns the basis of all earlier relations of production and intercourse, and for the first time consciously treats all natural premises as the creatures of hitherto existing men, strips them of their natural character and subjugates them to the power of the united individuals. Its organisation is, therefore, essentially economic, the material production of the conditions of this unity; it turns existing conditions into conditions of unity. The reality, which communism is creating, is precisely the true basis for rendering it impossible that anything should exist independently of individuals, insofar as reality is only a product of the preceding intercourse of individuals themselves.

The German Ideology (1845/46)
Context: The fact is, therefore, that definite individuals who are productively active in a definite way enter into these definite social and political relations. Empirical observation must in each separate instance bring out empirically, and without any mystification and speculation, the connection of the social and political structure with production. The social structure and the state are continually evolving out of the life-process of definite individuals, but of individuals, not as they appear in their own or other people's imagination, but as they really are; i. e. as they are effective, produce materially, and are active under definite material limits, presuppositions and conditions independent of their will.
The production of ideas, of conceptions, of consciousness, is at first directly interwoven with the material activity and the material intercourse of men, the language of real life. Conceiving, thinking, the mental intercourse of men, appear at this stage as the direct efflux of their material behaviour. The same applies to mental production as expressed in the language of the politics, laws, morality, religion, metaphysics of a people. Men are the producers of their conception, ideas, etc. — real, active men, as they are conditioned by a definite development of their productive forces and of the intercourse corresponding to these, up to its furthest forms. Consciousness can never be anything else than conscious existence, and the existence of men is their actual life-process. If in all ideology men and their circumstances appear upside down as in a camera obscura, this phenomenon arises just as much from their historical life-process as the inversion of objects on the retina does from their physical life-process.

Source: Critique of Hegel's Philosophy of Right

Louis ​Bonaparte brumaire tizennyolcadikája

A Kommunista Párt kiáltványa (Manifest der Kommunistischen Partei)
Source: A kiáltvány szövegét Friedrich Engellsel közösen készítette.

Original: Bevezetés a hegeli jogfilozófia kritikájához (Introduction to A Contribution to the Critique of Hegel’s Philosophy of Right)

A Kommunista Párt kiáltványa (Manifest der Kommunistischen Partei)
Source: A kiáltvány szövegét Friedrich Engellsel közösen készítette.

Original: Bevezetés a hegeli jogfilozófia kritikájához (Introduction to A Contribution to the Critique of Hegel’s Philosophy of Right)