What I remember above all about Harvard was being in the midst of so much energy and intelligence. It could be exhilarating, intimidating, sometimes even discouraging, but always challenging. It was an amazing privilege – and though I left early, I was transformed by my years at Harvard, the friendships I made, and the ideas I worked on. (来源：英语学习门户网站EnglishCN.com)

But taking a serious look back … I do have one big regret.

I left Harvard with no real awareness of the awful inequities in the world – the appalling disparities of health, and wealth, and opportunity that condemn millions of people to lives of despair.

I learned a lot here at Harvard about new ideas in economics and politics. I got great exposure to the advances being made in the sciences.

But humanity’s greatest advances are not in its discoveries – but in how those discoveries are applied to reduce inequity. Whether through democracy, strong public education, quality health care, or broad economic opportunity – reducing inequity is the highest human achievement.

I left campus knowing little about the millions of young people cheated out of educational opportunities here in this country. And I knew nothing about the millions of people living in unspeakable poverty and disease in developing countries.

It took me decades to find out.

You graduates came to Harvard at a different time. You know more about the world’s inequities than the classes that came before. In your years here, I hope you’ve had a chance to think about how – in this age of accelerating technology – we can finally take on these inequities, and we can solve them.

Imagine, just for the sake of discussion, that you had a few hours a week and a few dollars a month to donate to a cause – and you wanted to spend that time and money where it would have the greatest impact in saving and improving lives. Where would you spend it?

For Melinda and for me, the challenge is the same: how can we do the most good for the greatest number with the resources we have.

During our discussions on this question, Melinda and I read an article about the millions of children who were dying every year in poor countries from diseases that we had long ago made harmless in this country. Measles, malaria, pneumonia, hepatitis B, yellow fever. One disease I had never even heard of, rotavirus, was killing half a million kids each year – none of them in the United States.

We were shocked. We had just assumed that if millions of children were dying and they could be saved, the world would make it a priority to discover and deliver the medicines to save them. But it did not. For under a dollar, there were interventions that could save lives that just weren’t being delivered.

If you believe that every life has equal value, it’s revolting to learn that some lives are seen as worth saving and others are not. We said to ourselves: “This can’t be true. But if it is true, it deserves to be the priority of our giving.”