http://www.marxists.org/archive/marx/works/1880/soc-utop/ch03.htm
Let us briefly sum up our sketch of historical evolution.
I. Mediaeval Society — Individual production on a small scale. Means of production adapted for individual use; hence primitive, ungainly, petty, dwarfed in action. Production for immediate consumption, either of the producer himself or his feudal lord. Only where an excess of production over this consumption occurs is such excess offered for sale, enters into exchange. Production of commodities, therefore, only in its infancy. But already it contains within itself, in embryo, anarchy in the production of society at large.
II. Capitalist Revolution — transformation of industry, at first by means of simple cooperation and manufacture. Concentration of the means of production, hitherto scattered, into great workshops. As a consequence, their transformation from individual to social means of production — a transformation which does not, on the whole, affect the form of exchange. The old forms of appropriation remain in force. The capitalist appears in his capacity as owner of the means of production, he also appropriates the products and turns them into commodities. Production has become a social act. Exchange and appropriation continue to be individual acts, the acts of individuals. The social product is appropriated by the individual capitalist. Fundamental contradiction, whence arise all the contradictions in which our present-day society moves, and which modern industry brings to light.
A. Severance of the producer from the means of production. Condemnation of the worker to wage-labor for life. Antagonism between the proletariat and the bourgeoisie.
B. Growing predominance and increasing effectiveness of the laws governing the production of commodities. Unbridled competition. Contradiction between socialized organization in the individual factory and social anarchy in the production as a whole.
C. On the one hand, perfecting of machinery, made by competition compulsory for each individual manufacturer, and complemented by a constantly growing displacement of laborers. Industrial reserve-army. On the other hand, unlimited extension of production, also compulsory under competition, for every manufacturer. On both sides, unheard-of development of productive forces, excess of supply over demand, over-production and products — excess there, of laborers, without employment and without means of existence. But these two levers of production and of social well-being are unable to work together, because the capitalist form of production prevents the productive forces from working and the products from circulating, unless they are first turned into capital — which their very superabundance prevents. The contradiction has grown into an absurdity. The mode of production rises in rebellion against the form of exchange.
D. Partial recognition of the social character of the productive forces forced upon the capitalists themselves. Taking over of the great institutions for production and communication, first by joint-stock companies, later in by trusts, then by the State. The bourgeoisie demonstrated to be a superfluous class. All its social functions are now performed by salaried employees.
III. Proletarian Revolution — Solution of the contradictions. The proletariat seizes the public power, and by means of this transforms the socialized means of production, slipping from the hands of the bourgeoisie, into public property. By this act, the proletariat frees the means of production from the character of capital they have thus far borne, and gives their socialized character complete freedom to work itself out. Socialized production upon a predetermined plan becomes henceforth possible. The development of production makes the existence of different classes of society thenceforth an anachronism. In proportion as anarchy in social production vanishes, the political authority of the State dies out. Man, at last the master of his own form of social organization, becomes at the same time the lord over Nature, his own master — free.
To accomplish this act of universal emancipation is the historical mission of the modern proletariat. To thoroughly comprehend the historical conditions and this the very nature of this act, to impart to the now oppressed proletarian class a full knowledge of the conditions and of the meaning of the momentous act it is called upon to accomplish, this is the task of the theoretical expression of the proletarian movement, scientific Socialism.