How money differs from other measures, and also from commodities.

21. In the idea of money, the quality of the material is supposed to be unchangeable, and to be universally or every where the same: And therefore, the material being once fixed or agreed upon; all that is to be included in the idea of money, is the quantity only of that material, as in other standard measures, whether of weight or extension: And the only essential difference betwixt them, is this; that money is not only a measure, but also an equivalent, and as such passes from one to another; whilst other measures, may rest indifferently in the buyer’s or seller’s, or a third person’s hands, it matters not whose they be.

Money also differs from all commodities in this, that, as such, its value is permanent or unalterable; that is, money being the measure of the values of all other things, and that, like all other standard measures, by its quantity only; its own value is to be deemed invariable: And all contracts or engagements, are to be deemed fully discharged and satisfied, by the payment of the specific quantity or sum of money, agreed upon; without having any regard to the value of money, with respect to other things, at the different times of contracting and discharging of debts.

This is a fundamental characteristic of money, without which, it would lose its use as such; nor can money, with any propriety, be considered as being subject to vary in its value, without referring it to something else as a standard; and thereby, departing from its use as money, and making it a mere commodity.