Answer:
The Preamble of the U.S. Constitution is that part.
Step-by-step explanation:
The Preamble perfectly embodies the Enlightenment idea that the people are the sovereign. "We the People..." It´s like saying that we, as sovereigns, decide to give ourselves this supreme law that will give us justice, provide for the common defense, promote our welfare and secure our freedoms. So, we "do ordain and establish this Constitution of the United States of America." Beautiful.