As far as Feuerbach is a materialist he does not deal with history, and as far as he considers history he is not a materialist. - Marx, German Ideology (1845)

Once we accept the point of view that human knowledge develops from ignorance, we shall find millions of examples of it just as simple as the discovery of alizarin in coal tar, millions of observations not only in the history of science and technology but in the everyday life of each and every one of us that illustrate the transformation of “things-in-themselves” into “things-for-us.” - Lenin, Materialism and Empirio-Criticism (1908)

And this life activity [the worker] sells to another person in order to secure the necessary means of life. ... He works that he may keep alive. He does not count the labor itself as a part of his life; it is rather a sacrifice of his life. It is a commodity that he has auctioned off to another. - Marx, Wage Labour and Capital (1847)

My dialectic method is not only different from the Hegelian, but is its direct opposite. .... With him it is standing on its head. It must be turned right side up again, if you would discover the rational kernel within the mystical shell. - Marx, Afterword to the Second German Edition of Capital (1873)

The prime factors in the question of stability are such members of the C.C. as Stalin and Trotsky. I think relations between them make up the greater part of the danger of a split. - Lenin, Letter to the Congress (1922)

It is at moments of need that one learns who one’s friends are. Defeated armies learn their lesson. - Lenin, Left-Wing Communism: An Infantile Disorder (1920)

So long as the state exists there is no freedom. When there is freedom, there will be no state. - Lenin, The State and Revolution (1917)

But the revolution is thoroughgoing. It is still traveling through purgatory. It does its work methodically. ... And when it has accomplished this second half of its preliminary work, Europe will leap from its seat and exult: Well burrowed, old mole! - Marx, Eighteenth Brumaire of Louis Bonaparte (1852)

Are we to build the Party on the basis of that already formed and welded core of Social-Democrats which brought about the Party Congress, for instance, and which should enlarge and multiply Party organisations of all kinds; or are we to content ourselves with the soothing phrase that all who help are Party members? - Lenin, One Step Forward, Two Steps Back, “Paragraph One of the Rules” (1904)

Men make their own history, but they do not make it as they please; they do not make it under self-selected circumstances, but under circumstances existing already, given and transmitted from the past. The tradition of all dead generations weighs like an nightmare on the brains of the living. - Marx, Eighteenth Brumaire of Louis Bonaparte (1852)

But the working class cannot simply lay hold of the ready-made state machinery, and wield it for its own purposes. - Marx, The Paris Commune (1871)

Only your small-minded German philistine who measures world history by the ell and by what he happens to think are ‘interesting news items’, could regard 20 years as more than a day where major developments of this kind are concerned, though these may be again succeeded by days into which 20 years are compressed. - Marx, Marx To Engels (9 April 1863)

The Socialists of oppressed nations must, in their turn, unfailingly fight for the complete (including organisational) unity of the workers of the oppressed and oppressing nationalities. - Lenin, Socialism and War (1915)

The country that is more developed industrially only shows, to the less developed, the image of its own future. - Marx, Preface to First German Edition of Capital (1867)

If tomorrow, Morocco were to declare war on France, India on England, Persia or China on Russia, and so forth, those would be “just” “defensive” wars, irrespective of who attacked first; and every Socialist would sympathise with the victory of the oppressed, dependent, unequal states against the oppressing, slave-owning, predatory “great” powers. - Lenin, Socialism and War (1915)

Human anatomy contains a key to the anatomy of the ape. - Marx, The Grundrisse (1857)

All efforts and all attention should now be concentrated on the next step — the search after forms of the transition or the approach to the proletarian revolution. - Lenin, Left-Wing Communism: An Infantile Disorder (1920)

It is not difficult to be a revolutionary when revolution has already broken out and is in spate, when all people are joining the revolution just because they are carried away, because it is the vogue, and sometimes even from careerist motives. It is far more difficult—and far more precious—to be a revolutionary when the conditions for direct, open, really mass and really revolutionary struggle do not yet exist. - Lenin, Left-Wing Communism: An Infantile Disorder (1920)

In general it is always empirical businessmen we are talking about when we refer to political economists, (who represent) their scientific creed and form of existence. - Marx, Human Requirements and Division of Labour (1844)

The philosophers have only interpreted the world, in various ways; the point is to change it. - Marx, Theses On Feuerbach: Thesis 11 (1845)