The powers of the federal government are enumerated; it can only operate in certain cases; it has legislative powers on defined and limited objects, beyond which it cannot extend its jurisdiction.
James Madison (1836). “The Debates in the Several State Conventions on the Adoption of the Federal Constitution: As Recommended by the General Convention at Philadelphia in 1787. Together with the Journal of the Federal Convention, Luther Martin's Letter, Yates's Minutes, Congressional Opinions, Virginia and Kentucky Resolutions of '98-'99, and Other Illustrations of the Constitution”, p.95