ABSTRACT
From all we have learnt about values, gentlemen, the result is that an exchange completed, or at least possible, is the only means we have of ensuring ourselves of the value of a thing. We buy a commodity by means of another; but in order to know the value of the former, we need to know the value of the latter. From this point, the quantity of the former we are obliged to give informs us of the value of the other.
