Bill Gates famously dropped out of Harvard University in 1975 after two years of study and started Microsoft with Paul Allen soon thereafter. On Thursday, he returned to the Ivy League school to take part in a Q&A with students.

Provost Alan Garber and Dean Frank Doyle welcomed Gates, who opened by discussing his time at Harvard — as a freshman yearbook image projected behind him on the stage showed the software and philanthropic pioneer as a young man.

“People say I’m a dropout, which is literally true, but because i like online courses … I like going to college more than anyone,” Gates said about his voracious appetite for reading and learning about all sorts of subjects these days.

Before taking questions from students, Gates reminded them of his optimistic belief that today is a great and exciting time to be alive.

“In this generation, cancer, infectious disease — so many things will be solved,” Gates said.

Watch the video above for the complete conversation, and here are a few highlights:

Q. What is something you regret doing or not doing at Harvard?

Gates: “I wish I’d been more sociable. I was so anti-social, Steve Ballmer decided I needed to have some exposure to, I guess, drinking. That was highly educational. I wish I’d mixed around a bit more. It was a fun time though, because you had people around you could talk to 24 hours a day. The classes were so interesting, and they fed you. .. I wish I’d gotten to know people, I was just so into the classes and being good at the classes. … It worked out in the end.”

Q. What do you regard as the most significant challenge facing the U.S. today and in coming decades?

Gates: “If you had to pick one I’d say the quality of the education system. This is a country that has, essentially, a credo of equal opportunity more than anything else. The only way you really execute equal opportunity is by having a great education system. There are a few other issues, like staying out of wars would be a good thing. … If I had one for the world I’d fix malnutrition, and one for the U.S. I’d pick education.”

Q. When did you recognize it was time to delegate?

Gates: “If you want to have impact, usually delegation is important. When Microsoft first got started I wrote most of the code, and everybody else’s code I read and kind of rewrote. That got us up to 10 people and I said, ‘OK, we are going to ship code that I didn’t edit,’ and that was hard for me. … And then I said, ‘Well, I’m going to interview everyone and I’m at least going to look at samples of their code.’ That got us up to about 40 people. … That’s when I hired Steve [Ballmer] and Steve figured out a.) how to control what promises I made to people and b.) how to hire lots of people and really good people.”

Q. Regarding your philosophy on parenting, what if your child wants to drop out of school?

Gates: “My eldest graduates from Stanford in June, so, I’m optimistic. … I have to say, I’ve delegated … not delegated … my wife does 80 percent of this, she’s a way better parent than I am.”

Q. If you suddenly found yourself to be a sophomore at Harvard today what would you study?

Gates: “The thing that you’re likely to be world class at, is whatever you obsessed over from age 12 to 18. In my case it was writing software. Today I would go into software, which today that means going into artificial intelligence. Computers still can’t read. They cannot take a book of information and say, pass an AP test on that book. That’s a solvable problem. I’ve always wanted to solve that problem, I’m jealous that maybe one of you gets to work on that. I’m unlikely to go back and be hands on in that. But it’s the juiciest problem ever, I’ve thought about it for a long time. So I would go into AI.”