To refer the power in question to the clause "to provide for the common defense and general welfare" would be contrary to the established and consistent rules of interpretation, as rendering the special and careful enumeration of powers which follow the clause nugatory and improper. Such a view of the Constitution would have the effect of giving to Congress a general power of legislation instead of the defined and limited one hitherto understood to belong to them, the terms "common defense and general welfare" embracing every object and act within the purview of a legislative trust.