The great work of Marx may be described as an exposition and criticism of capital. But it is also indirectly an exposition of socialism, inasmuch as the historical evolution of capital is governed by natural laws, the inevitable tendency of which is towards socialism. It is the great aim of Marx to reveal the law of the economic movement of modern times. Now, the economic movement of modern times is dominated by capital. Explain, therefore, the natural history of capital, the rise, consolidation, and decline of its supremacy as an evolutionary process, and you forecast the nature of that into which it is being transformed—socialism. Hence the great task of the Marx school is not to preach a new economic and social gospel, not to provide ready-made schemes of social regeneration after the fashion of the early socialists, nor to counteract by alleviating measures the wretchedness of our present system, but to explain and promote the inevitable process of social evolution, so that the domination of capital may run its course and give place to the higher system that is to come.

The characteristic feature of the régime of capital, or, as Marx usually calls it, the capitalistic method of production, is, that industrial operations are carried on by individual capitalists employing free labourers, whose sole dependence is the wage they receive. Those free labourers perform the function fulfilled in other states of society by the slave and the serf. In the development of the capitalistic system is involved the growth of the two classes,—the capitalist class, enriching itself on the profits of industry, which they control in their own interest, and the class of workers, nominally free, but without land or capital, divorced, therefore, from the means of production, and dependent on their wages—the modern proletariat. The great aim of the capitalist is the increase of wealth through the accumulation of his profits. This accumulation is secured by the appropriation of what the socialists call surplus value. The history of the capitalistic method of production is the history of the appropriation and accumulation of surplus value. To understand the capitalistic system is to understand surplus value. With the analysis of value, therefore, the great work of Marx begins.

The wealth of the societies in which the capitalistic method of production prevails appears as an enormous collection of commodities. A commodity is in the first place an external object adapted to satisfy human wants; and this usefulness gives it value in use, makes it a use value. These use values form the material of wealth, whatever its social form may be. In modern societies, where the business of production is carried on to meet the demands of the market, for exchange, these use values appear as exchange values. Exchange value is the proportion in which use values of different kinds exchange for each other. But the enormous mass of things that circulate in the world market exchange for each other in the most different proportion. They must, however, have a common quality, or they could not be compared. This common quality cannot be any of the natural properties of the commodities. In the business of exchange one thing is as good as another, provided you have it in sufficient quantity.

Leaving out of consideration, therefore, the physical qualities that give commodities use value, we find in them but one common characteristic—that they are all products of human labour. They are all crystallised forms of human labour. It is labour applied to natural objects that gives them value. What constitutes value is the human labour embodied in commodities. And the relation of exchange is only a phase of this value, which is therefore to be considered independently of it. Further, the labour time spent in producing value is the measure of value, not this or that individual labour, in which case a lazy or unskilled man would produce as great a quantity of value as the most skilful and energetic. We must take as our standard the average labour force of the community. The labour time which we take as the measure of value is the time required to produce a commodity under the normal social conditions of production with the average degree of skill and intensity of labour. Thus labour is both the source and the measure of value.

The conditions necessary to the existence and growth of capitalism, therefore, are as follows:—A class, who have a virtual monopoly of the means of production; another class of labourers, who are free, but destitute of the means of production; and a system of production for exchange in a world market. But it may be asked how these historical conditions were established? How did the capitalist class originate, and how were the workers divorced from the instruments of labour, and how was the world market opened up?

Such a state of things was established only after a long and gradual process of change, which Marx copiously illustrates from the history of England, as the classic land of the fully developed capitalism. In the Middle Ages the craftsman and peasant were the owners of the small means of production then extant, and they produced for their own needs and for their feudal superior; only the superfluity went into the general market. Such production was necessarily small, limited, and technically imperfect. Towards the close of the Middle Ages a great change set in, caused by a remarkable combination of circumstances—the downfall of the feudal system and of the Catholic Church, the discovery of America and of the sea route to India. Through the breaking-up of the feudal houses with their numerous retainers, through the transformation of the old peasant-holdings into extensive sheep-runs, and generally through the prevalent application of the commercial system to the management of land, instead of the Catholic and feudal spirit, the peasantry were driven off the land; a multitude of people totally destitute of property were thrown loose from their old means of livelihood, and were reduced to vagabondage or forced into the towns. It was in this way that the modern proletarians made their tragic entry in history.

On the other hand, there was a parallel development of the capitalist class, brought about by the slave-trade, by the exploitation of the American colonies and of both the Indies, and by the robbery, violence, and corruption which attended the transference of the land from the Catholic and feudal to the modern régime. The opening and extension of the vast world market, moreover, gave a great stimulus to industry at home. The old guilds having already been expropriated and dissolved, the early organisation of industry under the control of an infant capitalism passed through its first painful and laborious stages, till, with the great mechanical inventions, with the application of steam as the motive-power, and the rise of the factory system towards the close of the eighteenth century, the great industrial revolution was accomplished, and the capitalistic method of production attained to its colossal manhood.

Thus the capitalistic system was established. And we must remember that in all its forms and through all the stages of its history the great aim of the capitalist is to increase and consolidate his gains through the appropriation of surplus value. We have now to inquire how this surplus value is obtained?

The starting-point of the capitalistic system is the circulation of wares. As we have seen, the capitalistic method of production is dominated by exchange. If exchange, however, consisted merely in the giving and receiving of equivalents, there could be no acquisition of surplus value. In the process of exchange there must appear something the utilisation of which by the buyer yields a greater value than the price he pays for it.

The thing desired is found in the labour force of the workman, who, being destitute of the means of production, must have recourse to the owner of these, the capitalist. In other words, the workman appears on the market with the sole commodity of which he has to dispose, and sells it for a specified time at the price it can bring, which we call his wage, and which is equivalent to the average means of subsistence required to support himself and to provide for the future supply of labour (in his family). But the labour force of the workman, as utilised by the capitalist in the factory or the mine, produces a net value in excess of his wage; that is, over and above his entire outlay, including the wage paid to his workmen, the capitalist finds himself in possession of a surplus, which can only represent the unpaid labour of his workmen. This surplus is the surplus value of Karl Marx, the product of unpaid labour.