To interpret the labor movement means to offer a theory of the struggle between labor and capital in our present society. According to Karl Marx, the founder of modern socialism, the efficient cause in all the class struggles of history has been technical progress. Progress in the mode of making a living or the growth of "productive forces," says Marx, causes the coming up of new classes and stimulates in each and all classes a desire to use their power for a maximum class advantage. Referring to the struggle between the class of wage earners and the class of employers, Marx brings out that modern machine technique has concentrated the social means of production under the ownership of the capitalist, who thus became absolute master. The laborer indeed remains a free man to dispose of his labor as he wishes, but, having lost possession of the means of production, which he had as a master-workman during the preceding handicraft stage of industry, his freedom is only an illusion and his bargaining power is no greater than if he were a slave. But capitalism, Marx goes on to say, while it debases the worker, at the same time produces the conditions of his ultimate elevation. Capitalism with its starvation wages and misery makes the workers conscious of their common interests as an exploited class, concentrates them in a limited number of industrial districts, and forces them to organize for a struggle against the exploiters. The struggle is for the complete displacement of the capitalists both in government and industry by the revolutionary labor class. Moreover, capitalism itself renders effective although unintended aid to its enemies by developing the following three tendencies: First, we have the tendency towards the concentration of capital and wealth in the hands of a few of the largest capitalists, which reduces the number of the natural supporters of capitalism. Second, we observe a tendency towards a steady depression of wages and a growing misery of the wage-earning class, which keeps revolutionary ardor alive. And lastly, the inevitable and frequent economic crises under capitalism disorganize it and hasten it on towards destruction. The last and gravest capitalistic industrial crisis will coincide with the social revolution which will bring capitalism to an end. The wage-earning class must under no condition permit itself to be diverted from its revolutionary program into futile attempts to "patch-up" capitalism. The labor struggle must be for the abolition of capitalism.