the State law, and, further, providing that the State law does not impair the obligation of contracts.[67] 28. But State insolvent laws apply to contracts within the State between one of its citizens and a citizen of another State, and they do not apply to contracts not made within the State. The principle here is one of jurisdiction: no State has authority outside its own jurisdiction. Therefore interstate matters are beyond State jurisdiction and are exclusively under the control of Congress. This principle is expressed judicially: “Insolvent laws of one State cannot discharge the contracts of citizens of other States because they have no extra-territorial operation.”[68] 29. Congress exercises any of its powers as an agent of its sovereign, the people of the United States. These powers, like those of the President, or of the federal courts, are expressed or implied; the government of the United States is “a national government with sovereign powers, legislative, executive, and judicial.”[69] Because this government is a sovereign government it possesses the choice of means to make its sovereignty real. Hence it possesses power to pay the debts of the United States, to borrow money, to incorporate banks, to coin money, to make war, and to do whatever acts it considers necessary and proper, and in such manner as it sees fit,—all acts of sovereignty. It alone can determine what is a legal tender, what the value of coins, domestic or foreign (within its jurisdiction) and, in brief it can do all acts such “as accord with the usage of sovereign governments.” Thus the national currency may be coin or paper, as Congress shall regulate. Whatsoever Congress by legislation declares to be a legal tender in payment of debts between individuals or corporations is thereby a legal tender, because Congress is “the legislature of a sovereign nation” and is expressly empowered by the Constitution to enact laws of the kind.[70] This power is commensurate with the jurisdiction of Congress in this matter,—a power which absolutely and totally excludes the power of the several States. 30. As a matter of constitutional law, it must be admitted that, granting the national sovereignty of the people of the United States, it must follow that the legislature of this sovereign nation would possess such power over currency and coinage. That is, the power would be _implied_ if it were not expressed. It is the office or function of a supreme national government to legislate for national ends and purposes.[71]