4 SOCIAL SCIENTlSr of productive capital, P . . . P', and III) the circuit of commodity capital, C' . . . C". The capitalist begins with a certain amount of money capital M; he buys commodities in the form of means of production and labour power, which he engages in a production process P, from which emerges another set of commoditities G' which in turn becomes commodity capital when the capitalist takes it to the market to be exchanged for a larger sum of money M'. This is how individual capital accomplishes its self-expansion.4 ^ It can be presented schematically as follows: II M — C . . . P . . . C7 — M7 — C' . . . P' . . . C/' — M" — III The three circuits of capital are overlapping, such that any particular unit of capital simultaneously belongs to all the circuits at any given moment. The conditions of movement of the three types of capital, however, are not uniform. The history of evolution of imperialism illustrates the point. In the classical era of imperialism, of which Adam Smith, Ricardo and Marx wrote, it was commodity capital that crossed the national boundary of advanced capitalist country in the form of exported goods. The next phase of imperialism, which was identified by Lenin, saw the internationalization of money capital, that is, the "export of capital." In the latest phase of imperialism, the productive capital is internationalized as transnational corporations spread their wings. "The circuits of the individual capitals intertwine, presuppose and necessitate one another, and form precisely in this interlacing, the movement of the total social capital."6 Here we note two distinct concepts, namely, individual capital and social capital. Marx observes: \ The fact that the social capital is equal to the sum of the individual capitals (including the joint-stock capital or the state capital, so far as governments employ productive wage-labour in mines, railways etc., perform the function of industrial capitalists), and that the aggregate movement of social capital is equal to the algebraic sum of the movements of the individual capitals, does not in any way preclude the possibility that this movement as the movement of a single individual capital, may present other phenomena than the same