in Order to form a more perfect Union, establish Justice, insure domestic Tranquility, provide for the common defence

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.

The Declaration of Independence declares:

It asserts that all men are endowed with unalienable rights, including "Life, Liberty and the pursuit of Happiness," and that government’s purpose is to secure these rights.