It was not long after Kenneth Arrow's path-breaking study of social choice, Social Choice and Individual Values, was published in New York in 1951, that my brilliant co-student Sukhamoy Chakravarty drew my attention to the book and to Arrow's stunning "impossibility theorem" (this must have been in the early months of 1952). Sukhamoy too was broadly attracted by the left, but also worried about political authoritarianism, and we discussed the implications of Arrow's demonstration that no non-dictatorial social choice mechanism may yield consistent social decisions.

In Ge Hong's A Handbook of Prescriptions for Emergencies (肘后备急方), I noticed one sentence "A handful of Qinghao immersed in two liters of water, wring out the juice and drink it all" (青蒿一握, 以水二升渍, 绞取汁, 尽服之) when Qinghao was mentioned for alleviating malaria fevers. Most herbs were typically boiled in water and made into a decoction before taken by the patients. This unique way of using Qinghao gave me the idea that heating during extraction might have destroyed the active components and the high temperature might need to be avoided in order to preserve the herb's activity.

And this is where, a couple of years before I had become CEO, I had read this book by Carol Dweck out of Stanford [University] called “Mindset,” which was more in relation to my kids. And the simple concept in that book, which I loved a lot, was it's better to be a learn-it-all even if the know-it-all has more innate capability, because the learn-it-all ultimately will do better. And I said, well, that applies to CEOs. That applies to companies made up of people. And I said: What if we introduce that as the meme to have the cultural dialogue at Microsoft?

I read Stephen Pinker's The Better Angels of Our Nature a few years ago and got to talk to him about it after, which was a lot of fun. I reviewed it for my blog, Gates Notes, because I wanted other people to read it, love it, and hopefully learn from it the way I did. It's probably my favorite book and the one I recommend most often.

As I was starting my academic career, it was almost considered to be a negative signal to your career to get involved in politics ... But to me that was a sign you were doing something useful.

It was probably a series of biographies of scientists like Pasteur, or even earlier ones — Leeuwenhoek inventing the microscope and Madame Curie. I forget how many others, but it was really just, for me, a fascination to learn about these great heroes. At that time, of course, they were totally inaccessible, almost non-human, to me. It became very interesting to me.

I certainly want to continue trying to understand how the global environment functions. The earth as a system is a very complicated one. And to understand it, we need very many disciplines, very many different scientists working together. I want to continue working with my specialty, which is chemistry, with the atmosphere. There is still much to learn about chemical reactions that occur out there in the air, in the atmosphere. So one of my projects now is to really learn more about this pollution that occurs in cities and that is spreading more through the globe. To learn it in enough detail so we can better tackle it, we can better come up with new ways of using energy, for example, that are not so damaging to the environment.

Certainly not. As a young child, I remember just dreaming about the Nobel Prize, but that was just a dream. It’s not something I would have ever thought was possible for me.

I have also benefited from teaching; as I try to explain my views to students with critical and open minds, I find myself continually being challenged to go back and rethink ideas. I now see teaching and research as complementary, mutually reinforcing activities.

At first the research did not seem to be particularly interesting – I carried out a systematic search for processes that might destroy the CFCs in the lower atmosphere, but nothing appeared to affect them. We knew, however, that they would eventually drift to sufficiently high altitudes to be destroyed by solar radiation. The question was not only what destroys them, but more importantly, what the consequences are.