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“If Congress can employ money indefinitely to the general welfare, and are the sole and supreme judges of the general welfare, they may take the care of religion into their own hands; they may appoint teachers in every State, county and parish and pay them out of their public treasury; they may take into their own hands the education of children, establishing in like manner schools throughout the Union; they may assume the provision of the poor; they may undertake the regulation of all roads other than post-roads; in short, every thing, from the highest object of state legislation down to the most minute object of police, would be thrown under the power of Congress. Were the power of Congress to be established in the latitude contended for, it would subvert the very foundations, and transmute the very nature of the limited Government established by the people of America.”
James Madison
Letter to Edmund Pendleton
January 21, 1792

"The powers delegated by the proposed Constitution to the Federal Government, are few and defined. Those which are to remain in the State Governments are numerous and indefinite. The former will be exercised principally on external objects, as war, peace, negociation, and foreign commerce; with which last the power of taxation will for the most part be connected. The powers reserved to the several States will extend to all the objects, which, in the ordinary course of affairs, concern the lives, liberties and properties of the people; and the internal order, improvement, and prosperity of the State."
James Madison, Federalist 45