( 19 )
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 ex-
