In Capital. Critique of Political Economy (1867), Marx proposes that the motivating force of capitalism is in the exploitation of labor, whose unpaid work is the ultimate source of surplus value. The owner of the means of production is able to claim the right to this surplus value because he or she is legally protected by the ruling regime through property rights and the legally established distribution of shares which are by law only to be distributed to company owners and their board members. The historical section shows how these rights were acquired in the first place chiefly through plunder and conquest and the activity of the merchant and "middle-man". In producing capital (produced goods), the workers continually reproduce the economic conditions by which they labour. Capital proposes an explanation of the "laws of motion" of the capitalist economic system, from its origins to its future, by describing the dynamics of the accumulation of capital, the growth of wage labour, the transformation of the workplace, the concentration of capital, commercial competition, the banking system, the decline of the profit rate, land-rents, et cetera.
The critique of the political economy of capitalism proposes that:
After two decades of economic study and preparatory work (especially regarding the theory of surplus value), the first volume appeared in 1867 as The Production Process of Capital. After Marx's death in 1883, from manuscripts and the first volume Engels introduced Volume II: The Circulation Process of Capital in 1885; and Volume III: The Overall Process of Capitalist Production in 1894. These three volumes are collectively known as Das Kapital.
Capital, Volume I (1867) is a critical analysis of political economy, meant to reveal the contradictions of the capitalist mode of production, how it was the precursor of the socialist mode of production and of the class struggle rooted in the capitalist social relations of production. The first of three volumes of Das Kapital, Kritik der politischen Ökonomie (Capital: Critique of Political Economy) was published on 14 September 1867, dedicated to Wilhelm Wolff and was the sole volume published in Marx’s lifetime.
Capital, Volume II, subtitled The Process of Circulation of Capital, was prepared by Engels from notes left by Marx and published in 1885. It is divided into three parts: The Metamorphoses of Capital and Their Circuits, The Turnover of Capital and The Reproduction and Circulation of the Aggregate Social Capital. In Volume II, the main ideas behind the marketplace are to be found: how value and surplus-value are realized. Its dramatis personae are not so much the worker and the industrialist (as in Volume I), but rather the money owner (and money lender), the wholesale merchant, the trader and the entrepreneur or functioning capitalist. Moreover, workers appear in Volume II, essentially as buyers of consumer goods and therefore as sellers of the commodity labour power, rather than producers of value and surplus-value—though this latter quality, established in Volume I, remains the solid foundation on which the whole of the unfolding analysis is based. Reading Volume II is of monumental significance to understanding the theoretical construction of Marx's whole argument. Marx himself quite precisely clarified this place in a letter sent to Engels on 30 April 1868: "In Book 1... we content ourselves with the assumption that if in the self-expansion process £100 becomes £110, the latter will find already in existence in the market the elements into which it will change once more. But now we investigate the conditions under which these elements are found at hand, namely the social intertwining of the different capitals, of the component parts of capital and of revenue (= s)". This intertwining, conceived as a movement of commodities and of money, enabled Marx to work out at least the essential elements, if not the definitive form, of a coherent theory of the trade cycle, based upon the inevitability of periodic disequilibrium between supply and demand under the capitalist mode of production (Mandel, 1978, Introdution to Volume II of Capital). Volume II of Capital has indeed been not only a sealed book, but also a forgotten one. To a large extent, it remains so to this very day. Part 3 is the point of departure for a topic given its Marxist treatment later in detail by Rosa Luxemburg, among others.