In addition to these persuasive considerations, it may be observed, that the same reasons which show the necessity of denying to the States the power of regulating coin, prove with equal force that they ought not to be at liberty to substitute a paper medium in the place of coin. Had every State a right to regulate the value of its coin, there might be as many different currencies as States, and thus the intercourse among them would be impeded; retrospective alterations in its value might be made, and thus the citizens of other States be injured, and animosities be kindled among the States themselves. The subjects of foreign powers might suffer from the same cause, and hence the Union be discredited and embroiled by the indiscretion of a single member. No one of these mischiefs is less incident to a power in the States to emit paper money, than to coin gold or silver. The power to make any thing but gold and silver a tender in payment of debts, is withdrawn from the States, on the same principle with that of issuing a paper currency. - from “The Federalist Papers, No. 44,” James Madison, 1788 Based on this excerpt, which BEST explains why Article I, Section 10 of the Constitution prohibits states from coining their own money