Answer:
The Necessary and Proper Clause establishes the powers that Congress has beyond those that are strictly stated in the Constitution, especially regarding the "implied powers". This Clause makes part of Article I, Section 8. These powers, which were not directly, and expressely given to the states, allowed Congress to pass legislation that was deemed necessary and proper for the proper governance of the nation, even if the laws went against state legislation. In this form, the Constitution gave Congress almost limitless powers, which did not make a lot of people in the new country happy.
Thomas Jefferson, as many of his peers, did not believe in unlimited powers, especially when taken away from the states, and given, implied, or not, to the federal government, including Congress. To him, this belied the very nature of the principles on which the U.S had been grounded and it opened up for him a huge chasm when it came to how far Congress could go in its use of such "implied" powers to set laws for proper governance. As such, there were measures that were taken by Congress, like the establishment of a National Bank, that to him were unnecessary, and which showed that the Clause had taken away any limitations that may exist to the power that Congress was allowed to exert in its perception of what was needed for proper and needed governance.
