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 estimate of its value by or to the individual, the haggling of the market, supply and demand, and so forth. The average of the prices paid for an article is its market price which will always be governed by the social value of the substance sold.

What is this social value common to all commodities? It is human labour. A thing has exchange value only in so far as human labour, physical or mental, is embodied in it. And it is not merely labour under any conditions. What determines the value of an article is the socially necessary labour contained in it, that is, the amount of average human labour necessary for its production under the given conditions of society. If anyone uses more or less labour, that does not alter the exchange value of the article which is measured only by the socially necessary labour. Further, if more articles are produced than under the existing social condition can be distributed for use, the exchange value of such articles will fall. If the tools of production are improved, then during the first period of transition, when the old methods are still the generally accepted methods of production, the value of an article is measured according to the human labour socially necessary with the old system of production, whereas when the new system becomes the more prevalent, the value is measured according to this new system.

All this applies to all commodities, including the peculiar commodity, labour power, which, whilst belonging to the individual, and inseparable from him, is in the capitalist mode of production, unlike that in all former modes of production, bought and sold like any other commodity. Like all other commodities when bought by the capitalist, the price paid for the worker's labour-power is in accordance with the necessary social labour contained in its reproduction, that is, he will have to pay the labourer in wages the amount which, under the given conditions of life, the labourer needs for his maintenance and for the propagation of his species. This will, of course, vary with the standard of life, with the supply and demand of labour, with the degree of association of the labourers for their common interests, and so forth. But so long as only one portion of society is engaged in production, whilst the