JohnRM
Don't make me destroy you
We the people of the United States, in order to form a more perfect union, establish justice, insure domestic tranquility, provide for the common defense, promote the general welfare, and secure the blessings of liberty to ourselves and our posterity, do ordain and establish this Constitution for the United States of America.
That is a preamble. It is a summarization of what is contained in the U.S. Constitution. It does not grant any power to the government whatsoever. If it did, the remainder of the Constitution would be rendered useless and redundant as the government would have unlimited power to do whatever it wishes as long as it claimed it was doing so for the general welfare of the nation.
preamble; A preliminary introduction to a statute or constitution (usually explaining its purpose)