John Hughes is one of the most naturally talented writers in the business. He can lock himself up in his house for two weeks and come out with a culturally-defining story that will continue to touch generations to come.
Ferris Bueller is a significant movie because it illustrates the journey of life in one day, which I think is why he does more in one day than is physically possible. Cameron--always doubting himself even though he is talented (which we see when he successfully pretends to be the Sausage King of Chicago). Ferris--living by the carpe diem philosophy and being fulfilled and liked by everyone as a result.
I think that one of the most significant moments in the film is one that is transitory in nature and not one that anyone sees as important. When the bell signalling class starting rings, a boy drops his books and no one stops and takes the time to help him pick them up. I know that this moment had some sort of symbolic meaning about the apathy of people, but I find it so significant because it is so simple--so real.
When I saw this, I was managing a theater. A bunch of the managers from the chain went to watch it together.
At the end, we all looked at each other. "Did you like it?" I asked. "I think so," they all replied. We were not sure at first what we really thought. Then we all agreed that it was a great little movie. The crowds the next day proved that.