Optimism, for me, is not a passive expectation that things are going to get better.

For me, it's a conviction and a belief that we can make things better.

So no matter how much suffering we see, no matter how bad it is, we can help people if we don't lose hope help and if we don't look away.

(Applause).

BILL GATES: 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 fuels innovation and leads to new approaches that eliminate suffering.

But if you never really see the people that are suffering, your optimism can't help them.

You will never change their world.

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

The modern world is an incredible source of innovation and Stanford stands at the center of that, creating new companies, new schools of thought, prize-winning professors, inspired art and literature, miracle drugs, and amazing graduates.

Whether you are a scientist with a new discovery, or working in the trenches to understand the needs of the most marginalized, you are advancing amazing breakthroughs in what human beings can do for each other.

At the same time, if you ask people across the United States is the future going to be better than the past, most say no.

My kids will be worse off than I am.

They think innovation won't make the world better for them or their children.

So who is 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 are not crazy.

If innovation is purely market driven, and we don't focus on the big inequities, then we could have amazing advances and in inventions that leave the world even more divided.

We won't improve cure 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 channels our optimism, we will see the poverty and the disease and the poor schools.

We will answer with our innovations and we will surprise the pessimists.

Over the next generation, you, Stanford graduates, will lead a new wave of innovation.

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 are going to make our optimism matter to everyone, and empower people everyone, we have to see the lives of those most in need.

If we have optimism, without empathy, then it doesn't matter how much we master the secrets of science.

We are not really solving problems.

We are just working on puzzles.

I think most of you have a broader world view 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 are eager to see it.

(Applause).

MELINDA GATES: So let your heart break.

It will change what you do with your optimism.

On a trip to south Asia, I met a desperately poor Indian woman.

She had two children and she begged me to take them home with me.

And when I begged her for her forgiveness she said, well then, please, just take one of them.

On another trip to south Los Angeles, I met with a group of the students from a tough neighborhood.

A young girl said to me, do you ever feel like we are the kids' whose parents shirked their responsibilities and we are just the leftovers? These women broke my heart.

And they 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, there's no difference between what we want for our children.

The only difference is our ability to provide it to our children.

So what accounts for that difference?

Bill and I talk about this with our own kids around the dinner table.

Bill worked incredibly hard and he took risks and he made sacrifices for success.

But there's another essential ingredient of success, and that is luck.

Absolute and total luck. When were you born? Who are your parents?

Where did you grow up? None of us earn these things. These things were given to us.

So when we strip away all of our luck and our privilege and we consider where we would be without them, it becomes someone much easier to see someone who is poor and say, that could be me.

And that's empathy. Empathy tears down barriers and it opens up whole new frontiers for optimism.

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

You don't have to rush. You have careers to launch and debts to pay and spouses to meet and marry.

That's plenty enough for right now. But in the course of your lives, perhaps without any plan on your part, you will see suffering that's going to break your heart.

And when it happens, don't turn away from it. That's the moment that change is born.

Congratulations and good luck to the class of 2014!