The preamble establishes the principle that the government derives its powers from the people and introduces the six purposes of the government in serving the people.
Explanation:
"We the People of the United States [power derived from the people] , 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 [six purposes] to ourselves and our Posterity, do ordain and establish this Constitution for the United States of America."
