Bill Gates: Congratulations, Class of 2014! Melinda and I are excited to be here. It would be a thrill for anyone to be invited to speak at a Stanford Commencement – but it’s especially gratifying for us.

Stanford is rapidly becoming the favorite university for members of our family. And it’s long been a favorite university for Microsoft and our foundation. Our formula has been to get the smartest, most creative people working on the most important problems. It turns out that a disproportionate number of those people are at Stanford.

Right now, we have more than 30 foundation research projects underway with Stanford. When we want to learn more about the immune system to help cure the worst diseases, we work with Stanford. When we want to understand the changing landscape of higher education in the United States so that more low-income students get college degrees, we work with Stanford.

This is where genius lives.

There is a flexibility of mind here – an openness to change, an eagerness for what’s new. This is where people come to discover the future and have fun doing it.

Melinda Gates: Some people call you nerds – and you claim the label with pride.

Bill: Well, so do we.

There are so many remarkable things going on here at this campus. But if Melinda and I had to put into one word what we love most about Stanford, it’s the optimism. There’s an infectious feeling here that innovation can solve almost every problem.

That’s the belief that drove me, in 1975, to leave a college in the suburbs of Boston and go on an endless leave of absence. I believed that the magic of computers and software would empower people everywhere and make the world much, much better.

It’s been almost 40 years since then, and 20 years since Melinda and I were married. We are both more optimistic now than ever. But on our journey together, our optimism evolved. We’d like to tell you what we learned – and talk to you today about how your optimism and ours can do more – for more people.

When Paul Allen and I started Microsoft, we wanted to bring the power of computers and software to the people – and that was the kind of rhetoric we used. One of the pioneering books in the field had a raised fist on the cover, and it was called Computer Lib. At that time, only big businesses could buy computers. We wanted to offer the same power to regular people – and democratize computing.

By the 1990s, we saw how profoundly personal computers could empower people. But that success created a new dilemma: If rich kids got computers and poor kids didn’t, then technology would make inequality worse. That ran counter to our core belief: Technology should benefit everybody. So we worked to close the digital divide. I made it a priority at Microsoft, and Melinda and I made it an early priority at our foundation – donating personal computers to public libraries to make sure everyone had access.

The digital divide was a focus of mine in 1997 when I took my first trip to South Africa. I went there on business, so I spent most of my time in meetings in downtown Johannesburg. I stayed in the home of one of the richest families in South Africa. It had only been three years since the election of Nelson Mandela marked the end of apartheid. When I sat down for dinner with my hosts, they used a bell to call the butler. After dinner, the men and women separated, and the men smoked cigars. I thought, “Good thing I read Jane Austen, or I wouldn’t have known what was going on.”

The next day I went to Soweto – the poor township southwest of Johannesburg that had been a center of the anti-apartheid movement.

It was a short distance from the city into the township, but the entry was sudden, jarring, and harsh. I passed into a world completely unlike the one I came from.

My visit to Soweto became an early lesson in how naïve I was.

Microsoft was donating computers and software to a community center there – the kind of thing we did in the United States. But it became clear to me very quickly that this was not the United States.

I had seen statistics on poverty, but I had never really seen poverty. The people there lived in corrugated tin shacks with no electricity, no water, no toilets. Most people didn’t wear shoes; they walked barefoot along the streets. Except there were no streets – just ruts in the mud.

The community center had no consistent source of power, so they had rigged up an extension cord that ran about 200 feet from the center to a diesel generator outside. Looking at the setup, I knew the minute the reporters and I left, the generator would get moved to a more urgent task, and the people who used the community center would go back to worrying about challenges that couldn’t be solved by a PC.

When I gave my prepared remarks to the press, I said: “Soweto is a milestone. There are major decisions ahead about whether technology will leave the developing world behind. This is to close the gap.”

As I was reading those words, I knew they were irrelevant. What I didn’t say was: “By the way, we’re not focused on the fact that half a million people on this continent are dying every year from malaria. But we’re sure as hell going to bring you computers.”

Before I went to Soweto, I thought I understood the world’s problems, but I was blind to the most important ones. I was so taken aback by what I saw that I had to ask myself, “Do I still believe that innovation can solve the world’s toughest problems?”

I promised myself that before I came back to Africa, I would find out more about what keeps people poor.

Over the years, Melinda and I did learn more about the most pressing needs of the poor. On a later trip to South Africa, I paid a visit to a hospital for patients with MDR-TB, or multi-drug-resistant tuberculosis, a disease with a cure rate of under 50 percent.

I remember that hospital as a place of despair. It was a giant open ward with a sea of patients shuffling around in pajamas, wearing masks.

There was one floor just for children, including some babies lying in bed. They had a little school for the kids who were well enough to learn, but many of the children couldn’t make it, and the hospital didn’t seem to know whether it was worth it to keep the school open.

I talked to a patient there in her early thirties. She had been a worker at a TB hospital when she came down with a cough. She went to a doctor, and he told her she had drug-resistant TB. She was later diagnosed with AIDS. She wasn’t going to live much longer, but there were plenty of MDR patients waiting to take her bed when she vacated it.

This was hell with a waiting list.

But seeing hell didn’t reduce my optimism; it channeled it. I got in the car and told the doctor who was working with us: “Yeah, I know. MDR-TB is hard to cure. But we should be able to do something for these people.” This year, we’re entering phase three with a new TB drug regime. For patients who respond, instead of a 50 percent cure rate after 18 months for $2,000, we could get an 80-90 percent cure rate after six months for under $100.

That’s better by a factor of a hundred.

Optimism is often dismissed as false hope. But there is also false hopelessness.

That’s the attitude that says we can’t defeat poverty and disease.

We absolutely can.

Melinda: Bill called me after he visited the TB hospital. Ordinarily, if we’re calling from a trip, we just go through the agenda of the day: “Here’s what I did; here’s where I went; here’s who I met.” But this call was different. He said: “Melinda, I’ve gone somewhere I’ve never been before” and then he choked up and couldn’t talk. Finally he just said: “I’ll tell you when I get home.”

I knew what he was going through. When you see people with so little hope, it breaks your heart. But if you want to do the most, you have to see the worst. That’s what Bill was doing that day. I’ve had days like that, too.

Ten years ago, I traveled to India with friends. On the last day there, I spent some time meeting with prostitutes. I expected to talk to them about the risk of AIDS, but they wanted to talk about stigma. Most of these women had been abandoned by their husbands, and that’s why they’d gone into prostitution. They were trying to make enough money to feed their kids. They were so low in the eyes of society that they could be raped and robbed and beaten by anybody – even by police – and nobody cared.

Talking to them about their lives was so moving to me. But what I remember most is how much they wanted to touch me and be touched. It was as if physical contact somehow proved their worth. As I was leaving, we took a photo of all of us with our arms linked together.

Later that day, I spent some time in a home for the dying. I walked into a large hall and saw rows and rows of cots. Every cot was attended except for one far off in the corner that no one was going near, so I walked over there. The patient was a woman who seemed to be in her thirties. I remember her eyes. She had these huge, brown, sorrowful eyes. She was emaciated, on the verge of death. Her intestines weren’t holding anything – so they had put her on a cot with a hole cut out in the bottom, and everything just poured through into a pan below.

I could tell she had AIDS, both from the way she looked, and the fact that she was off in the corner alone. The stigma of AIDS is vicious – especially for women – and the punishment is abandonment.

When I arrived at her cot, I suddenly felt totally helpless. I had absolutely nothing I could offer her. I knew I couldn’t save her, but I didn’t want her to be alone. So I knelt down next to her and reached out to touch her – and as soon as she felt my hand, she grabbed it and wouldn’t let go. We sat there holding hands, and even though I knew she couldn’t understand me, I just started saying: “It’s okay. It’s okay. It’s not your fault. It’s not your fault.”

We had been there together for a while when she pointed upward with her finger. It took me some time to figure out that she wanted to go up to the roof and sit outside while it was still light out. I asked one of the workers if that would be okay, but she was overwhelmed by all the patients she had to care for. She said: “She’s in the last stages of dying, and I have to pass out medicine.” Then I asked another, and got the same answer. It was getting late and the sun was going down, and I had to leave, and no one seemed willing to take her upstairs.

So finally I just scooped her up – she was just skin over a skeleton, just a sack of bones – and I carried her up the stairs. On the roof, there were a few of those plastic chairs that will blow over in a strong breeze, and I set her down on one of those, and I helped prop her feet up on another, and I placed a blanket over her legs.

And she sat there with her face to the west, watching the sunset. I made sure the workers knew that she was up there so they would come get her after the sun went down. Then I had to leave her.

But she never left me.

I felt completely and totally inadequate in the face of this woman’s death.

But sometimes it’s the people you can’t help who inspire you the most.

I knew that the sex workers I linked arms with in the morning could become the woman I carried upstairs in the evening – unless they found a way to defy the stigma that hung over their lives.

Over the past 10 years, our foundation has helped sex workers build support groups so they could empower each other to speak out for safe sex and demand that their clients use condoms. Their brave efforts helped keep HIV prevalence low among sex workers, and a lot of studies show that is a big reason why the AIDS epidemic in India hasn’t exploded.

When these sex workers gathered together to help stop AIDS transmission, something unexpected and wonderful happened. The community they formed became a platform for everything. They were able to set up speed-dial networks to respond to violent attacks. Police and others who raped and robbed them couldn’t get away with it anymore. The women set up systems to encourage savings. They used financial services that helped some of them start businesses and get out of sex work. This was all done by people society considered the lowliest of the low.

Optimism for me isn’t a passive expectation that things will get better; it’s a conviction that we can make things better – that whatever suffering we see, no matter how bad it is, we can help people if we don’t lose hope and we don’t look away.

Bill: Melinda and I have described some devastating scenes. But we want to make the strongest case we can for the power of optimism. Even in dire situations, optimism can fuel innovation and lead to new tools to eliminate suffering. But if you never really see the people who are suffering, your optimism can’t help them. You will never change their world.

And that brings me to what I see as a paradox.

The world of science and technology is driving phenomenal innovations – and Stanford stands at the center of that, creating new companies, prize-winning professors, ingenious software, miracle drugs, and amazing graduates. We’re on the verge of mind-blowing breakthroughs in what human beings can do for each other. And people here are really excited about the future.

At the same time, if you ask people across the United States, “Is the future going to be better than the past?” most people will say: “No. My kids will be worse off than I am.” They think innovation won’t make the world better for them or for their children.

So who’s right?

The people who say innovation will create new possibilities and make the world better?

… or …

The people who see a trend toward inequality and a decline in opportunity and don’t think innovation will change that?

The pessimists are wrong in my view, but they’re not crazy. If technology is purely market-driven and we don’t focus innovation on the big inequities, then we could have amazing inventions that leave the world even more divided.

We won’t improve public schools. We won’t cure malaria. We won’t end poverty. We won’t develop the innovations poor farmers need to grow food in a changing climate.

If our optimism doesn’t address the problems that affect so many of our fellow human beings, then our optimism needs more empathy. If empathy channeled our optimism, we would see the poverty and the disease and the poor schools, we would answer with our innovations, and we would surprise the pessimists.

Over the next generation, you Stanford graduates will lead a new wave of innovation and apply it to your world. Which problems will you decide to solve? If your world is wide, you can create the future we all want. If your world is narrow, you may create the future the pessimists fear.

I started learning in Soweto that if we’re going to make our optimism matter to everyone and empower people everywhere, we have to see the lives of those most in need. If we have optimism, but we don’t have empathy – then it doesn’t matter how much we master the secrets of science, we’re not really solving problems; we’re just working on puzzles.

I think most of you have a broader worldview than I had at your age. You can do better at this than I did. If you put your hearts and minds to it, you can surprise the pessimists. We can’t wait to see it.

Melinda: Let your heart break. It will change what you do with your optimism.

On a trip to South Asia, I met a desperately poor mother who brought me her two small children and implored me: “Please take them home with you.” When I begged her forgiveness and said I could not, she said: “Then please take one.”

On another trip, to South Los Angeles, I was talking to a group of high school students from a tough neighborhood when one young woman said to me: “Do you ever feel like we are just somebody else’s kids whose parents shirked their responsibilities, that we’re all just leftovers?”

These women made my heart break – and still do. And the empathy intensifies if I admit to myself: “That could be me.”

When I talk with the mothers I meet during my travels, I see that there is no difference at all in what we want for our children. The only difference is our ability to give it to them.

What accounts for that difference?

Bill and I talk about this with our kids at the dinner table. Bill worked incredibly hard and took risks and made sacrifices for success. But there is another essential ingredient of success, and that ingredient is luck – absolute and total luck.

When were you born? Who were your parents? Where did you grow up? None of us earned these things. They were given to us.

When we strip away our luck and privilege and consider where we’d be without them, it becomes easier to see someone who’s poor and sick and say “that could be me.” This is empathy; it tears down barriers and opens up new frontiers for optimism.

So here is our appeal to you: As you leave Stanford, take your genius and your optimism and your empathy and go change the world in ways that will make millions of others optimistic as well.

You don’t have to rush. You have careers to launch, debts to pay, spouses to meet and marry. That’s enough for now.

But in the course of your lives, without any plan on your part, you’ll come to see suffering that will break your heart.

When it happens, and it will, don’t turn away from it; turn toward it.

That is the moment when change is born.

Congratulations and good luck.