species or forms of currency does the Constitution allow, and what does it forbid? It is plain enough that this depends on what we understand by currency. Currency, in a large, and, perhaps, in a just sense, includes not only gold, and silver, and bank notes, but bills of exchange also. It may include all that adjusts exchanges and settles balances in the operations of trade and business. But if we understand by currency the legal money of the country, and that which constitutes a lawful tender for debts, and is the statute measure of value, then, undoubtedly, nothing is included but gold and silver. Most unquestionably there is no legal tender, and there can be no legal tender, in this country, under the authority of this government or any other, but gold and silver, either the coinage of our own mints, or foreign coins, at rates regulated by Congress. This is a constitutional principle perfectly plain, and of the very highest importance. The States are expressly prohibited from making anything but gold and silver a tender, in payment of debts, and although no such express prohibition is applied to Congress, yet as Congress has no power granted to it, in this respect, but to coin money and to regulate the value of foreign coins, it clearly has no power to substitute paper, or anything else, for coin, as a tender in payment of debts and in discharge of contracts. Congress has exercised this power, fully, in both its branches. It has coined money, and still coins it. It has regulated the value of foreign coins, and still regulates their value. The legal tender, therefore, the constitutional standard of value, is established, and cannot be overthrown. To overthrow it, would shake the whole system. But, if the Constitution knows only gold and silver as a legal tender, does it follow that the Constitution cannot tolerate the voluntary circulation of bank notes, convertible into gold and silver at the will of the holder, as part of the actual money of the country? Is a man not only to be entitled to demand gold and silver for every debt, but is he, or should he be, obliged to demand it in all cases? Is it, or should government make it, unlawful to receive pay in anything else? Such a notion is too absurd to be seriously treated. The constitutional tender is the thing to be preserved, and it ought to be preserved sacredly, under all circumstances. The rest remains for judicious legislation by those who have competent authority.”
That is a very emphatic expression of opinion on the part of Mr. Webster, and it is often cited. He puts this doctrine as
