18. Of the powers delegated to Congress by the American people it may be said that, save as excepted by the silence of the Constitution, or by positive limitation, they are universal and affirmative. Their extent as well as their nature are made known by interpretation,—that is, through the judiciary.[49] Judicial interpretation must be distinguished from economic, industrial, political, or even moral interpretation. The Constitution provides only for judicial interpretation.[50] The American people have vested legislative powers in Congress, and the exercise of them by Congress must be measured by the terms of the grant.[51] Thus far the supreme test of the constitutional exercise of these powers is to compare the particular act of Congress with the Constitution. Shall the act overrule the Constitution, or shall the Constitution overrule the act? This is the final test of congressional exercise of powers delegated; it is the essential measure of federal legislation. Practically it is congressional legislation which, sooner or later, brings out clearly,—or at least as clearly as the government of the United States can bring out,—the real nature of that government. Thus it is congressional legislation which, as tested in the courts of law, brings into view the implied and inherent powers of the federal government; the relations of that government with the States, and the powers of that government as to territories and outlying possessions.[52] So, too, it is congressional legislation that determines the objects and the extent of taxation, both direct and indirect; that regulates commerce, coins money, and fixes its value; affords equal protection to citizens, and applies the police power of the United States. It is congressional legislation which largely determines the jurisdiction of federal courts and assigns duties and powers to the President.[53] In brief, the legislative powers vested in Congress reflect the convictions of the people of the United States of the eighteenth century, when the trend of political thought was to dethrone kings and to enthrone legislatures, with basic regard for individualism. A like tendency and regard are discernible in the State constitutions of that period. The American people did not create an omnipotent Congress, but they created a Congress having few limitations and these they practically nullified by the “sweeping clause” which empowers Congress “to make all laws which shall be necessary and proper for carrying into execution,” the powers granted, “and all other powers vested by this Constitution in the government of the United States, or in any department or officer thereof.”[54] 19. The phrase “necessary and proper” practically includes all the purposes of government, and these the Constitution itself sets forth, as