'No very early day will probably witness the reduction of the public debt to the amount required as a basis for secured circulation. Should no future wars arrest reduction and again demand expenditures beyond revenue, that day will, however, at length come. When it shall arrive the debt may be retained on low interest at that amount, or some other security for circulation may be devised, or, possibly, the vast supplies of our rich mines may render all circulation unadvisable except gold and the absolute representatives and equivalents, dollar for dollar, of gold in the treasury or on safe deposit elsewhere. But these considerations may be for another generation. 'The Secretary forbears extended argument on the constitutionality of the suggested system. It is proposed as an auxiliary to the power to borrow money; as an agency of the power to collect and disburse taxes; and as an exercise of the power to regulate commerce, and of the power to regulate the value of coin. Of the two first sources of power nothing need be said. The argument relating to them was long since exhausted, and is well known. Of the other two there is not room, nor does it seem needful to say much. If Congress can prescribe the structure, equipment, and management of vessels to navigate rivers flowing between or through different States as a regulation of commerce, Congress may assuredly determine what currency shall be employed in the interchange of their commodities, which is the very essence of commerce. Statesmen who have agreed in little else have concurred in the opinion that the power to regulate coin is, in substance and effect, a power to regulate currency, and that the framers of the Constitution so intended. It may well enough be admitted that while Congress confines its regulation to weight, fineness, shape, and device, banks and individuals may issue notes for currency in competition with coin. But it is difficult to conceive by what process of logic the unquestioned power to regulate coin can be separated from the power to maintain or restore its circulation, by excluding from currency all private or corporate substitutes which affect its value, whenever Congress shall see fit to exercise that power for that purpose. 'The recommendations, now submitted, of the limited issue of United States notes as a wise expedient for the present time, and as an occasional expedient for future times, and of the organization of banking associations to supply circulation secured by national bonds and convertible always into United States notes, and after resumption of specie payments, into coin, are prompted by no favor to excessive issues of any description of credit money.