For its part, the theory of money and trade explains how any given form of matter can take on a signifying function by being related to an object and serving as a permanent sign for it; it also explains (by the interaction of trade and the increase and diminution of the quantity of specie) how this relation of sign to the thing signified can be modified without ever disappearing, how the same monetary element can signify more or less wealth, how it can shift, dilate, and shrink in relation to the values it has the task of representing.