A Diploma Among Many by Dave McCaul

The weekend of my college graduation was a blur. Both my parents and grandparents flew in for the occasion. There were receptions, dances, meals, and parties. With so many things to do, and so many people to see, it was easy to forget why we were celebrating.
When everything was back to normal, I took my diploma out of its envelope for a closer look. It listed my full name, my degree (a B. A. in International Studies), and the years of my attendance. The diploma itself was an inadequate expression of the education I had received.
I thought back to when I first arrived at college. I'd acquired some bad habits in high school, only I didn't realize they were bad habits. It took some of my professors to point them out to me. There was the time that my Freshman English professor took me aside after class, for example.
"How are you liking Ralph Waldo Emerson?" he asked me.
He was asking because we'd just been debating Emerson's essay, "Self-Reliance."
"I think it's wonderful," I told him.
"Well, don't be shy about it," he said.
I knew what he meant by this. During the debate in class, I hadn't said a word.
"Look, I can tell you're smart," he said. "If you're looking for a pretty good education, you're in the right place." He paused and stroked his beard for a moment. "But if you want a truly excellent education, it will take some extra effort. You're going to have to participate a bit more."
Over the next four years, the professor's advice stuck with me. I hoped I'd never forget it. It meant a lot more to me than a piece of paper with a few dates on it.

What happens in the flashback of the passage?