What is the genius of the constitution?

There is a particular scene in "With Honors", a movie that, it is said, lampoons the presidency of Ronald Reagan (1981-1989), that I like best because it is the only scene that I managed to watch so far, thanks to Youtube. Professor Pitkannan, the heady professor of government, once asked his students what is the genius of the constitution?

Monty (played by Brendan Fraser) gave an answer, a flimsy one.

Monty :  The president can't bomb without reason.
Professor Pitkannan: He has a reason. He thinks we need more parking spaces. The point is, can he destroy the world?
Monty: Not without Congress
Professor Pitkannan: The President can make a war in 90 days without consulting Congress.

It was only after indulging in the language of insult with Simon Wilder (played by Joe Pesci) did the professor receive a brilliant answer to his question.

Wilder: The genius of the constitution is that it can always be changed. The genius of the constitution is that it makes no permament rule other than its faith in the wisdom of ordinary people to govern themselves.
Professor Pitkannan: Faith in the wisdom of its people is exactly what makes the constitution incomplete and crude.
Wilder: Crude! No sir. Our founding parents...were white farmers. But they were also great men because they know one thing that all great men should know: That they didn't know everything. They knew they were gonna make mistakes.  They made sure they leave a way to correct them. They didn't think of themselves as leaders. They wanted a government of citizens, not royalty; a government of listeners, not lecturers; a government that could change, not stand still. A president isn't an elective King, no matter how many bombs he can drop because the crude constitution doesn't trust him.  He's the servant of the people. He's just a bum. The only bliss he's searching for is freedom and justice.