step 2 profit "Conceptual framework" published by the financial accounting standards board Under the theoretical framework of the theory, the theory of commodity market equilibrium and the monetary market equilibrium of Keynesian theory are unified. Marx's theory of interest rate decisions from the perspective of the source and essence of interest, taking into account the institutional factors in the role of interest rate decisions of interest theory, its theoretical core is the interest rate is determined by the average profit margin. Marx believed that under capitalism, interest is a part of profit and a form of conversion of surplus value. From the total formula of capital, G- w-g, the surplus value is created in the process of direct production, which is also realized in the process of circulation. So, it seems to capitalist surplus value is the proliferation of all capital in advance, because (1) as for the cost of capital, in order to produce goods, he not only to advance capital to buy the Labour force, but also bought consumed in the process of production of a variety of means of production, these fees by capital purchase price as a factor of production to join the formation of the cost price; (2) in terms of the capital, capital purchased in advance of production and labor under the direction and supervision of the capitalists, in the process of production, play the function of the production of surplus value, not only the cost of capital is involved in the formation of the surplus value, and all the upfront capital as the material factors of production (including those not yet take fixed capital), in the whole process of production, to participate in the formation process of the surplus value, therefore, all the capital should be paid in advance. The residual value is not only the increase of the capital, but also the total capital increase. These are all distorted surface phenomena. In fact, the value of proliferation is just hired laborers in the process of production created the new value of the cost of living, the balance after deduct the labor price (wages), as the proliferation of alterable capital or hire workers free of charge for the rest of the product of Labour, is surplus value. The surplus value, as a product of the concept of total prepaid capital, is the transformation form of profit.