which it produces in the course of a day is double its own value for the day is fortunate for the buyer but according to the laws of exchange no injustice to the seller. The laborer then costs the owner of money according to our calculation the value product of six hours' labor, but he gives him daily the value product of twelve hours' labor. The difference to the credit of the owner of the money is six hours' unpaid extra labor, an unpaid for surplus product, in which the labor of six hours is incorporated. The trick is done. Surplus value is produced, money is transformed into capital. While Marx, in this way, proved how surplus value exists and the only possible way in which it can exist, under the laws which regulate the exchange of commodities he also exposed the present capitalistic methods of production and the methods of appropriation resting upon them and unveiled the secret upon which the whole arrangement of the society of to-day depends. There is a necessary presupposition to this origin and birth of capital. "For the transformation of money into capital the money owner must first find free laborers in the market, free in the double sense that as a free person the laborer can use his labor power as a commodity, that he has no other wares to sell, that he is unemployed and that he is free of everything necessary to the realisation of his labor power." But this condition of a possessor of money or commodities on the one hand, and, on the other, of the possessor of nothing, except his own labor force, is no natural condition of affairs nor is it common to all periods of history; "it is clearly the result of a historical development, the product of a whole series of older forms of social production." And this free laborer first strikes our notice as a historical phenomenon at the end of the fifteenth and the beginning of the sixteenth century as a result of the dissolution of feudal society. Thereupon with the creation of the world trade and the world market which dates from the same period the foundation was laid for the mass of moveable wealth to become more and more transformed into capital and for the capitalistic system, directed more and more to the production of surplus value, to become the dominant system. _VIII. Capital and Surplus Value (Conclusion)._ (Duehring having said that the term surplus value merely signifies in ordinary language, rent, profit and interest, Engels still further explains)