represent a given quantity of labour, it is obvious that labour stands quite alone in this respect, and that it is the quantity of _labour_ which a commodity will command, and not the quantity of any other commodity, which can represent the conditions of its supply, or its natural value.[D] It will be allowed, then, First, that when commodities are obtained by labour alone, and sold immediately, they will, on an average, exchange with each other according to the quantity of labour employed upon them. Secondly, that when profits are concerned, and differ either in rate or quantity, commodities can no longer exchange with each other, according to the quantity of labour employed upon them, except by accident. Thirdly, that the quantity of accumulated and immediate labour applied to their production, must, in all the less complex cases, form the advances on which profits may be correctly calculated. And, fourthly, that when profits are calculated upon these advances, a quantity of labour is obtained, according to which it is found, by experience, that commodities do exchange with each other in the same country; and, further, that this quantity of labour not only expresses correctly their value in exchange with each other, but their absolute and natural value in reference to the conditions of their supply. * * * * * In proceeding to consider what takes place in different countries where the value of the precious metals is very different, it will readily be acknowledged, that the rate at which commodities exchange with each other is not proportioned to the labour which has been employed upon them, with the addition of profits. And it is quite certain, that they cannot be proportioned to the quantity of labour alone of which they are composed. We know, from experience, that the commodities of different countries are actually exchanged with each other according to their money prices at the time. These prices must be determined partly by those natural elements of value which determine the rate at which commodities exchange with each other, and the natural conditions of their supply in each country, and partly by the different value of the precious metals in different situations, which must necessarily have a most powerful effect on the rate at which foreign commodities are exchanged. Knowing then the elements of the natural and relative value of commodities in the same country, if we knew also the difference in the value of money in different countries, we should know at once the rate at which the commodities of different countries would exchange with each other.