In so far as each single transaction invariably conforms to the laws of the exchange of commodities, the capitalist buying labor-power, the laborer selling it, and we will assume at its real value; in so far as all of this is true, it is evident that the laws of appropriation or of private property, laws that are based on the production and circulation of commodities, become by their own inner and inexorable dialectic changed into their very opposite. The exchange of equivalents, the original operation with which we started, has now become turned round in such a way that there is only an apparent exchange. This is owing to the fact, first, that the capital which is exchanged for labor-power is itself but a portion of the product of other’s labor appropriated without an equivalent; and, secondly, that this capital must not only be replaced by its producer, but replaced together with an added surplus. The relation of exchange subsisting between capitalist and laborer becomes a mere semblance appertaining to the process of circulation, a mere form, foreign to the real nature of the transaction, and only mystifying it. The ever-repeated purchase and sale of labor-power is now the mere form; what really takes place is this – the capitalist again and again appropriates, without equivalent, a portion of the previously materialized labor of others, and exchanges it for a greater quantity of living labor. At first the rights of property seemed to us to be based on a man’s own labor. [...] Now, however, property turns out to be the right, on the part of the capitalist, to appropriate the unpaid labor of others or its products, and to be the impossibility, on the part of the laborer, of appropriating his own product. The separation of property from labor has become the necessary consequence of a law that apparently originated in their identity. Marx, Capital, Volume 1 (Progress Publishers, 1887), p.412-413

In so far as each single transaction invariably conforms to the laws of the exchange of commodities, the capitalist buying labor-power, the laborer selling it, and we will assume at its real value; in so far as all of this is true, it is evident that the laws of appropriation or of private property, laws that are based on the production and circulation of commodities, become by their own inner and inexorable dialectic changed into their very opposite. The exchange of equivalents, the original operation with which we started, has now become turned round in such a way that there is only an apparent exchange. This is owing to the fact, first, that the capital which is exchanged for labor-power is itself but a portion of the product of other’s labor appropriated without an equivalent; and, secondly, that this capital must not only be replaced by its producer, but replaced together with an added surplus. The relation of exchange subsisting between capitalist and laborer becomes a mere semblance appertaining to the process of circulation, a mere form, foreign to the real nature of the transaction, and only mystifying it. The ever-repeated purchase and sale of labor-power is now the mere form; what really takes place is this – the capitalist again and again appropriates, without equivalent, a portion of the previously materialized labor of others, and exchanges it for a greater quantity of living labor. At first the rights of property seemed to us to be based on a man’s own labor. [...] Now, however, property turns out to be the right, on the part of the capitalist, to appropriate the unpaid labor of others or its products, and to be the impossibility, on the part of the laborer, of appropriating his own product. The separation of property from labor has become the necessary consequence of a law that apparently originated in their identity. Marx, Capital, Volume 1 (Progress Publishers, 1887), p.412-413

To be sure, the matter looks quite different if we consider capitalist production in the uninterrupted flow of its renewal, and if, in place of the individual capitalist and the individual worker, we view in their totality, the capitalist class and the working class confronting each other. But in so doing we should be applying standards entirely foreign to commodity production. Only buyer and seller, mutually independent, face each other in commodity production. The relations between them cease on the day when the term stipulated in the contract they concluded expires. If the transaction is repeated, it is repeated as the result of a new agreement which has nothing to do with the previous one and which only by chance brings the same seller together again with the same buyer. If, therefore, commodity production, or one of its associated processes, is to be judged according to its own economic laws, we must consider each act of exchange by itself, apart from any connexion with the act of exchange preceding it and that following it. And since sales and purchases are negotiated solely between particular individuals, it is not admissible to seek here for relations between whole social classes. However long a series of periodical reproductions and preceding accumulations the capital functioning today may have passed through, it always preserves its original virginity. So long as the laws of exchange are observed in every single act of exchange the mode of appropriation can be completely revolutionised without in any way affecting the property rights which correspond to commodity production. These same rights remain in force both at the outset, when the product belongs to its producer, who, exchanging equivalent for equivalent, can enrich himself only by his own labour, and also in the period of capitalism, when social wealth becomes to an ever- increasing degree the property of those who are in a position to appropriate continually and ever afresh the unpaid labour of others. This result becomes inevitable from the moment there is a free sale, by the labourer himself, of labour-power as a commodity. But it is also only from then onwards that commodity production is generalised and becomes the typical form of production; it is only from then onwards that, from the first, every product is produced for sale and all wealth produced goes through the sphere of circulation. Only when and where wage labour is its basis does commodity production impose itself upon society as a whole; but only then and there also does it unfold all its hidden potentialities. To say that the supervention of wage labour adulterates commodity production is to say that commodity production must not develop if it is to remain unadulterated. To the extent that commodity production, in accordance with its own inherent laws, develops further, into capitalist production, the property laws of commodity production change into the laws of capitalist appropriation. Marx, Capital, Volume 1, p.414-415