according as the current coin is more or less exactly agreeable to its standard, or contains more or less exactly the precise quantity of pure gold or pure silver which it ought to contain. If in England, for example, forty-four guineas and a half contained exactly a pound weight of standard gold, or eleven ounces of fine gold and one ounce of alloy, the gold coin of England would be as accurate a measure of the actual value of goods at any particular time and place as the nature of the thing would admit. But if, by rubbing and wearing, forty-four guineas and a half generally contain less than a pound weight of standard gold; the diminution, however, being greater in some pieces than in others; the measure of value comes to be liable to the same sort of uncertainty to which all other weights and measures are commonly exposed.