“If anything is certain, it is that I myself am not a Marxist.[In a letter about the peculiar 'Marxism' which arose in France 1882]”

“I am nothing but I must be everything.”

“Once the inner connection is grasped, all theoretical belief in the permanent necessity of existing conditions collapses before their collapse in practice-- Letter to Ludwig Kugelmann (July 11, 1868)”

“Merely quantitative differences, beyond a certain point, pass into qualitative changes.”

“In the social production of their existence, men inevitably enter into definite relations, which are independent of their will, namely relations of production appropriate to a given stage in the development of their material forces of production. The totality of these relations of production constitutes the economic structure of society, the real foundation, on which arises a legal and political superstructure and to which correspond definite forms of social consciousness. The mode of production of material life conditions the general process of social, political and intellectual life. It is not the consciousness of men that determines their existence, but their social existence that determines their consciousness. At a certain stage of development, the material productive forces of society come into conflict with the existing relations of production or – this merely expresses the same thing in legal terms – with the property relations within the framework of which they have operated hitherto. From forms of development of the productive forces these relations turn into their fetters. Then begins an era of social revolution. The changes in the economic foundation lead sooner or later to the transformation of the whole immense superstructure.”

“As a matter of fact, the methods of primitive accumulation are anything but idyllic.”

“...it is all the more clear what we have to accomplish at present: I am referring to ruthless criticism of all that exists, ruthless both in the sense of not being afraid of the results it arrives at and in the sense of being just as little afraid of conflict with the powers that be.”