The Preamble (the very first part) of the Constitution says the following:
" 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."
For the average citizen I think this clause is the most important because it establishes the Framers intent that the concept that "the general Welfare" of the nation's citizens is all important. To me, "the general Welfare" includes such things as, educational opportunities for all, employment opportunities for all, wellness care for all, as long as we ourselves are civicly responsible