„Der Philosoph legt sich – also selbst eine abstrakte Gestalt des entfremdeten Menschen – als den Maßstab der entfremdeten Welt an.“

—  Karl Marx, buch Ökonomisch-philosophische Manuskripte aus dem Jahre 1844

Paris Manuscripts (1844)

„Für die Welt arbeiten.“

—  Karl Marx

Paul Lafargue in: Karl Marx, Persönliche Erinnerungen, 1890, Abschnitt 1
Zugeschrieben

„Unser Wahlspruch muss also sein: Reform des Bewusstseins nicht durch Dogmen, sondern durch Analysirung des mystischen sich selbst unklaren Bewusstseins, trete es nun religiös oder politisch auf. Es wird sich dann zeigen, dass die Welt längst den Traum von einer Sache besitzt, von dem sie nur das Bewusstsein besitzen muss, um sie wirklich zu besitzen.“

—  Karl Marx

Ein Briefwechsel von 1843: Brief an [[w:Arnold Ruge|Arnold
Deutsch-Französische Jahrbücher (1844), Ein Briefwechsel von 1843

„Wenn Widerstand gegen die Macht der Sklavenhalter die maßvolle Losung Ihrer ersten Wahl war, so ist Tod der Sklaverei! der triumphierende Schlachtruf Ihrer Wiederwahl. […] Die Arbeiter Europas […] betrachten es als ein Wahrzeichen der kommenden Epoche, daß Abraham Lincoln, dem starksinnigen, eisernen Sohn der Arbeiterklasse, das Los zugefallen ist, sein Vaterland durch den beispiellosen Kampf für die Erlösung einer geknechteten Race und für die Umgestaltung der sozialen Welt hindurchzuführen.“

—  Karl Marx

An Abraham Lincoln, Präsident der Vereinigten Staaten von Amerika, im Namen der Internationalen Arbeiterassoziation. In: "Der Social-Demokrat" Nr. 3 vom 30. Dezember 1864. MEW Bd. 16, S. 18 f. mlwerke.de http://www.mlwerke.de/me/me16/me16_018.htm
(engl.: "If resistance to the Slave Power was the reserved watchword of your first election, the triumphant war cry of your re-election is Death to Slavery. [...] The workingmen of Europe [...] consider it an earnest of the epoch to come that it fell to the lot of Abraham Lincoln, the single-minded son of the working class, to lead his country through the matchless struggle for the rescue of an enchained race and the reconstruction of a social world." - marxists.org http://www.marxists.org/archive/marx/iwma/documents/1864/lincoln-letter.htm; Papers relating to the Foreign Affairs ... Part I 1866 p. 64
Über andere Personen

„Auf einer gewissen Stufe ihrer Entwicklung geraten die materiellen Produktivkräfte der Gesellschaft in Widerspruch mit den vorhandenen Produktionsverhältnissen oder, was nur ein juristischer Ausdruck dafür ist, mit den Eigentumsverhältnissen, innerhalb deren sie sich bisher bewegt hatten. Aus Entwicklungsformen der Produktivkräfte schlagen diese Verhältnisse in Fesseln derselben um. Es tritt dann eine Epoche sozialer Revolution ein. Mit der Veränderung der ökonomischen Grundlage wälzt sich der ganze ungeheure Überbau langsamer oder rascher um.“

—  Karl Marx

Zur Kritik der Politischen Ökonomie. Vorwort, 1859, MEW 13, S. 9
Zur Kritik der Politischen Ökonomie (1859)

„Aber wir können nicht immer den Stand ergreifen, zu dem wir uns berufen glauben; unsere Verhältnisse in der Gesellschaft haben einigermaßen schon begonnen, ehe wir sie zu bestimmen imstande sind.“

—  Karl Marx

Betrachtungen eines Jünglings bei der Wahl seines Berufes. (Abiturientenarbeit) MEW 40, S. 592

„Wilhelms [ Liebknecht ] in der Beilage abgedruckter Redeteil … zeigt innerhalb der Dummheit eine nicht zu leugnende Schlauheit, sich die Sache zurechtzumachen … Das Vieh glaubt an den zukünftigen 'Staat der Demokratie'! Unterderhand ist das bald das konstitutionelle England, bald die bürgerlichen Vereinigten Staaten, bald die elende Schweiz. Von revolutionärer Politik hat 'es' keine Ahnung.“

—  Karl Marx

Brief an Friedrich Engels, 1869, MEW 32, S. 360

„Wenn du nur für einen Tag oder zwei dagewesen wärst, hättest du genug Material anlegen können um für ein ganzes Jahr zu lachen. Darum war ich so bestrebt dich hier zu haben. So eine Gelegenheit bekommt man nicht jeden Tag geboten.“

—  Karl Marx

Über Ferdinand Lassalle, der bei Marx zu Besuch war, in einem Brief an Friedrich Engels, 1862. In selben Brief merkt Marx an, dass sich Lassalle seit seinem Aufenthalt in Zürich verändert habe. Übersetzung Wikiquote, Vgl. MEW 30, S. 257f.
engl.: "If you'd been here just for a day or two, you'd have been able to lay in enough material to keep you laughing for a whole year. That’s why I was so anxious to have you here. One doesn’t get an opportunity like that every day." - marxists.org http://www.marxists.org/archive/marx/works/1862/letters/62_07_30a.htm
Über andere Personen

„Die Proletarier dieser Welt haben nichts zu verlieren als ihre Ketten. Sie haben eine Welt zu gewinnen. Proletarier aller Länder, vereinigt euch!“

—  Karl Marx

„Communism… is the genuine resolution of the antagonism between man and nature and between man and man; it is the true resolution of the conflict between existence and essence, objectification and self-affirmation, freedom and necessity, individual and species. It is the riddle of history solved and knows itself as the solution.“

—  Karl Marx, buch Ökonomisch-philosophische Manuskripte aus dem Jahre 1844

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

„The oppressed are allowed once every few years to decide which particular representatives of the oppressing class shall represent and repress them in parliament.“

—  Karl Marx

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

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

—  Karl Marx, Eleven Theses on Feuerbach

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)
Quelle: Eleven Theses on Feuerbach

„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.“

—  Karl Marx

Remarks against personality cults from a letter to W. Blos (10 November 1877).
Kontext: 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.

„Where speculation ends — in real life — there real, positive science begins: the representation of the practical activity, of the practical process of development of men. Empty talk about consciousness ceases, and real knowledge has to take place.“

—  Karl Marx, buch Die deutsche Ideologie

Vol. I, Part 1, [The Materialist Conception of History].
The German Ideology (1845/46)
Kontext: Where speculation ends — in real life — there real, positive science begins: the representation of the practical activity, of the practical process of development of men. Empty talk about consciousness ceases, and real knowledge has to take place. When reality is depicted, philosophy as an independent branch of activity loses its medium of existence. At the best its place can only be taken by a summing-up of the most general results, abstractions which arise from the observation of the historical development of men. Viewed apart from real history, these abstractions have in themselves no value whatsoever. They can only serve to facilitate the arrangement of historical material, to indicate the sequence of its separate strata. But they by no means afford a recipe or schema, as does philosophy, for neatly trimming the epochs of history. On the contrary, our difficulties begin only when we set about the observation and the arrangement — the real depiction — of our historical material, whether of a past epoch or of the present.

„The development of fixed capital indicates in still another respect the degree of development of wealth generally, or of capital…“

—  Karl Marx, buch Grundrisse der Kritik der politischen Ökonomie

Notebook VII, The Chapter on Capital, pp. 628–629.
Grundrisse (1857/58)
Kontext: The development of fixed capital indicates in still another respect the degree of development of wealth generally, or of capital…
The creation of a large quantity of disposable time apart from necessary labour time for society generally and each of its members (i. e. room for the development of the individuals’ full productive forces, hence those of society also), this creation of not-labour time appears in the stage of capital, as of all earlier ones, as not-labour time, free time, for a few. What capital adds is that it increases the surplus labour time of the mass by all the means of art and science, because its wealth consists directly in the appropriation of surplus labour time; since value directly its purpose, not use value. It is thus, despite itself, instrumental in creating the means of social disposable time, in order to reduce labour time for the whole society to a diminishing minimum, and thus to free everyone’s time for their own development. But its tendency always, on the one side, to create disposable time, on the other, to convert it into surplus labour...
The mass of workers must themselves appropriate their own surplus labour. Once they have done so – and disposable time thereby ceases to have an antithetical existence – then, on one side, necessary labour time will be measured by the needs of the social individual, and, on the other, the development of the power of social production will grow so rapidly that, even though production is now calculated for the wealth of all, disposable time will grow for all. For real wealth is the developed productive power of all individuals. The measure of wealth is then not any longer, in any way, labour time, but rather disposable time. Labour time as the measure of value posits wealth itself as founded on poverty, and disposable time as existing in and because of the antithesis to surplus labour time; or, the positing of an individual’s entire time as labour time, and his degradation therefore to mere worker, subsumption under labour. The most developed machinery thus forces the worker to work longer than the savage does, or than he himself did with the simplest, crudest tools.

„The devil take this wrong arithmetic.“

—  Karl Marx, buch Grundrisse der Kritik der politischen Ökonomie

Notebook IV, The Chapter on Capital, p. 297.
Grundrisse (1857/58)
Kontext: The devil take this wrong arithmetic. But never mind.

„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.“

—  Karl Marx, buch Die deutsche Ideologie

Vol. I, Part 4.
The German Ideology (1845/46)
Kontext: 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.

„His latest proclamation, which is drafted in the same style, the manifesto abolishing slavery, is the most important document in American history since the establishment of the Union, tantamount to the tearing up of the old American Constitution.“

—  Karl Marx

Comments on the North American Events (1862)
Kontext: Lincoln’s proclamation is even more important than the. Lincoln is a sui generis figure in the annals of history. He has no initiative, no idealistic impetus, cothurnus, no historical trappings. He gives his most important actions always the most commonplace form. Other people claim to be “fighting for an idea”, when it is for them a matter of square feet of land. Lincoln, even when he is motivated by, an idea, talks about “square feet”. He sings the bravura aria of his part hesitatively, reluctantly and unwillingly, as though apologising for being compelled by circumstances “to act the lion”. The most redoubtable decrees — which will always remain remarkable historical documents-flung by him at the enemy all look like, and are intended to look like, routine summonses sent by a lawyer to the lawyer of the opposing party, legal chicaneries, involved, hidebound actiones juris. His latest proclamation, which is drafted in the same style, the manifesto abolishing slavery, is the most important document in American history since the establishment of the Union, tantamount to the tearing up of the old American Constitution.

„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“

—  Karl Marx

Early Writings, translated and ed. by , p. 159. https://www.marxists.org/archive/marx/works/1844/epm/3rd.htm
Kontext: 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.