Focusing on the Constitution- by George Sweeney

"The government is for the people; and the misfortune was, that the people had no agency in the government before....If the government is to be binding on the people, are not the people the proper persons to examine its merits or defects?"
-Governor Edmund Randolph in THE DEBATES IN THE CONVENTION OF THE COMMONWEALTH OF VIRGINIA, ON THE ADOPTION OF THE FEDERAL CONSTITUTION.

The US Constitution was originally a combination of a national and federal constitution. It was national in that the authority came from the people in order to establish the new government. It was also federal because the states agreed to share and surrender certain authorities with the new government.

Question: Why does the authority for government come from the people that are governed?