As well as one of the hundred most influential people of 2004, 2005, 2006 and again in 2007.

Just think what you could have achieved...

[Laughter.]

...if you had stayed here another 2 years.

[Laughter and then applause.]

He enrolled at Harvard in the fall of 1973.

Keenly interested in computer science but without a definite study plan.

[Some laughing.]

In between intense poker games at Radcliffe, he met his future business partner, Steve Balmer.

And he developed a version of the programming language Basic for the first microcomputer.

And co-authored and published a paper on algorithms, with computer scientist Christos Papadimitriou.

Our speaker is a person of many talents.

A close friend in college amusingly recalls seeing him doze of during a prestigious Putnam math exam.

Despite this napping he scored remarkably well.

In his junior year he took a leave of absence from Harvard to devote his energies to Microsoft.

A company he had begun in 1975 with his friend Paul Allen.

Since 2000 he has begun to concentrate on a number of philanthropic endeavors.

Making extraordinary donations to various charitable organisations and scientific research programs around the world, through the Bill and Melinda Gates foundation.

After a 33 year leave of absence from his alma matter.

I am pleased to present to you Doctor William Gates.

[Standing Ovation.]

Thank you.

President Bach, former president Rudenstine, incoming president Faust, members of the Harvard corporation and the board of overseers.

Members of the faculty, parents and especially the graduates.

I've been waiting more than 30 years to say this.

Dad I always told you I'd come back and get my degree.

[Applause and some laughter.]

I wanna thank Harvard for this honour.

I'll be changing my job next year and it will be nice to finally have a college degree on my resume.

[Laughter.]

I applaud the graduates for taking a much more direct route to your degrees.

From our- my part I'm just happy that the Crimson called me Harvard's most successful drop out.

I guess that makes me valedictorian of my own special class.

I did the best of everyone who failed.

[Laughter.]

But I also want to be recognised as the guy who got Steve Balmer to drop out of business school.

[Laughter and then also applause.]

I'm a bad influence.

That's why I was invited to speak at your graduation.

If I'd spoken at your orientation fewer of you might be here today.

[Laughter then also applause.]

Harvard was a phenomenal experience for me.

Academic life was fascinating.

I used to sit in on lots of classes that I hadn't even signed up for.

And dorm life was terrific.

I lived up at Radcliffe, in Courier House.

[Cheering.]

There were always a lot of people in my dorm room late at night discussing things, because everyone knew that I didn't worry about getting up in the morning.

[Laughter.]

That's how I came to be the leader of the antisocial group.

We clunged each other as a way of validating our rejection of all those social people.

Radcliffe was a great place to live.

There were more women up there and most of the guys were math-science types.

The combination offered me the best odds, if you know what I mean.

[Laughing.]

That's where I learned the sad lesson that improving your odds doesn't guarantee you success.

[Laughing.]

One of my biggest memories of Harvard came in January 1975.

When I made a call from Courier House to a company in Albuquerque, New Mexico, that had begun making the worlds first personal computer.

I offered to sell them software.

I worried they would realize I was just a student in a dorm and hang up on me.

Instead they said, we're not quite ready, come see us in a month.

Which was a good thing because we hadn't written the software yet.

[Laughing.]

From that moment I worked day and night on the extra credit project that marked the end of my college education and the beginning of a remarkable journey with Microsoft.

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.

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 and economics and politics.

I got great exposure to the advances being made in the sciences.

But humanities greatest advances are not in its discoveries, but in how those discoveries are applied to reduce inequity.

[Applause.]

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 worlds inequities than the classes that came before.

In your years here I've 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 have 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 I 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 are dying every year in poor countries from diseases that we have long ago made harmless in this country.

Measles, malaria, pneumonia, hepatitis-b, yellow fever.

One disease that I had never heard of, rotavirus, was killing half a million children each year.

None of them in the United States.

We were shocked.

We had 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.

So we begin ou- began our work in the same way anyone here would begin it.

We asked, how could the world let these children die?

The answer is simple and harsh

The market did not reward saving the lives of these children and governments did not subsidise it.

So the children die because their mothers and fathers hadno power in the market and no voice in the system.

But you and I have both

We can make market for- forces work better for the poor if we can develop a more creative capitalism.

If we can stretch the reach of market forces so that more people can make a profit or at least earn a living, serving people who are suffering from the great inequities.

We can also press governments around the world to spend tax payer money in ways that better reflect the values of the people who pay the taxes.

If we can find approaches that meet the needs of the poor in ways that generate profits for business and votes for politicians, we will have found a sustainable way to reduce inequity in the world.

Now this task is open ended.

It can never be finished, but a conscious effort to answer this challenge can change the world.

I'm optimistic that we can do this.

But I talk to skeptics who claim there is no hope.

They say inequity has been with us since the beginning and will be with us until the end, because people just don't care.

I completely disagree.

I believe we have more caring than we know what to do with.

All of us here in this yard, at one time or another, have seen human tragedies that broke our heart.

And yet we did nothing.

Not because we don't care, but because we didn't know what to do.

If we had known how to help we would have acted.

The barrier to change is not too little caring.

It is too much complexity.

To turn caring into action, we need to see a problem, see a solution and see the impact.

But complexity blocks all three steps.

Even with the advent of the internet and 24 hour news, it is still a complex enterprise to get people to truly see the problems.

When an airplane crashes, officials immediately call a press conference.

They promise to investigate, determine the cause and prevent similar crashes in the futures.

But if the officials were brutally honest, they would say, "Of all the people in the world who died today from preventable causes, 1 half of 1 percent were on this plane.".

We're determined to do everything possible to solve the problem that took the lives of 1 half of 1 percent.

The problem is not just the plane crash but the millions of preventable deaths.

We don't read much about these deaths, the media covers what's new and millions of people dying is nothing new.

So it stays in the background where it's easy to ignore.

But even when we do see it or read about it, it's difficult to keep our eye- eyes on the problem.

It's difficult to look at suffering if the situation is so complex that we don't know how to help and so we look away.

If we can really see a problem, which is the first step, we come to the second step.

Cutting through the complexity to find a solution.

Finding solutions is essential if we want to make the most of our caring.

If we have clear and proven answers any time an organisation or an individual asks, "How can I help?", then we can get action.

And we can make sure that none of the caring in the world is wasted.

The complexity makes it hard to mark a path of action for everyone who cares and makes it hard for that caring to matter.

Cutting through complexity to find solutions runs through 4 predictable stages:

Determine a goal. Find the highest impact approach.

Deliver the technology ideal for that approach and in the mean time use the best application of technology you already have.

Whether it's something sophisticated like a new drug or something simple like a bed net.

The aids epidemic offers an example, the broad goal of course is to end the disease.

The highest leverage approach is prevention, the ideal technology would be a vaccine that gives life long immunity with a single dose.

So governments, drug companies and foundations are funding vaccine research.

But their work is likely to take more than a decade.

So in the mean time we have to work with what we have in hand and the best prevention approach we have now is getting people to avoid risky behavior.

Pursuing that goal starts the 4 step cycle again.

This is the pattern.

The crucial thing is to never stop thinking and working.

And never do what we did with malaria and tuberculosis in the 20th century.

Which is to surrender to complexity and quit.

The final step after seeing the problem and finding an approach, is to measure the impact of the work and to share that, success or failure, so that others can learn from the efforts.

You have to have the statistics, of course, you have to be able to show for example that a program is vaccinating million more- millions more children.

You have to be able to show for example a decline in the number of children dying from the diseases.

This is essential not just to improve the program but also to help draw more investment from business and government

But if you want to inspire people to participate, you have to show more than numbers.

You have to convey the human impact of the work.

So people can feel what saving a life means to the families affected.