From Patriot Post:
Our Constitution's principle author, James Madison, wrote, "The powers delegated by the proposed Constitution to the federal government are few and defined [and] will be exercised principally on external objects, as war, peace, negotiation and foreign commerce."
Concerning the legislature's authority, Thomas Jefferson asserted: "[G]iving [Congress] a distinct and independent power to do any act they please which may be good for the Union, would render all the preceding and subsequent enumerations of power completely useless. It would reduce the whole [Constitution] to a single phrase, that of instituting a Congress with power to do whatever would be for the good of the United States; and as sole judges of the good or evil, it would be also a power to do whatever evil they please. Certainly, no such universal power was meant to be given them. [The Constitution] was intended to lace them up straightly within the enumerated powers and those without which, as means, these powers could not be carried into effect."