Bill Gates shares the most important thing he's learned from Warren Buffett

Bill Gates Interview

Bill Gates shares his favorite memories from 25 years of friendship with Warren Buffett—and what he's learned from the "Oracle of Omaha."

This commentary was originally published on gatesnotes.com and LinkedIn.

I don't remember the exact day I first met most of my friends, but with Warren Buffett I do. It was 25 years ago: July 5, 1991.

I think the date stands out in my mind so clearly because it marked the beginning of a new and unexpected friendship for Melinda and me — one that has changed our lives for the better in every imaginable way.

Warren has helped us do two things that are impossible to overdo in one lifetime: learn more and laugh more.

Over the last quarter-century of our friendship, we've done a lot of both. Melinda and I often find ourselves recounting some gem of wisdom Warren shared with us, or, chuckling when we recall something funny he said or did.

To mark the anniversary of our friendship, I thought I would share some of my favorite memories of our time together. Warren and I also created a virtual reality film together at this year's Berkshire Hathaway Shareholder's Meeting, which you can watch on my blog.

An Awkward Start: At first glance, Warren and I may seem like a mismatch. I'm a technology nerd. He's an investor who doesn't use email. In fact, I never expected to be friends with him.

In 1991, when my mother called me to come out to our vacation home on Hood Canal to meet a group of friends, including Warren, I didn't want to go. I told her I was too busy at work. Warren would be interesting, my mother insisted. But I wasn't convinced. "Look, he just buys and sells pieces of paper. That's not real value added. I don't think we'd have much in common," I told her. Eventually, she persuaded me to go. I agreed to stay for no more than two hours before getting back to work at Microsoft.

Then I met Warren. He started asking me some questions about the software business and why a small company like Microsoft could expect to compete with IBM and what were the skill sets and the pricing. These were amazingly good questions that nobody had ever asked. We were suddenly lost in conversation and hours and hours slipped by. He didn't come across as a big shot investor. He had this modest way of talking about what he does. He was funny, but what impressed me most was how clearly he thought about the world. It was a deep friendship from our very first conversation.

Oreos for Breakfast: One thing that was surprising to learn about Warren is that he has basically stuck to eating what he liked when he was six years old. He did move past baby food, of course, but he mostly eats hamburgers, ice cream, and Coke. (That's one reason it's so fun to go out to dinner with him.) I remember one of the first times he stayed at our house and he opened up a package of Oreos to eat for breakfast. Our kids immediately demanded they have some too. He may set a poor example for young people, but it's a diet that somehow works for him.

"We love what you've done with the dining room, Warren!" When Warren invited Melinda and me to stay at his house in Omaha for the first time, he gave us a tour. When we got to the dining room, we saw that there were no seats on the chairs. Warren was as surprised as we were. "What's going on?" he said, examining his chairs. Eventually, he learned that the cushions had been removed months before to get reupholstered, but he had not noticed until then. (He must have been eating his Oreos and ice cream in the kitchen.) We've been laughing about that visit ever since.

For World-Class Advice, Press 2: At my office I have just two numbers on speed dial: my home and Warren. If Warren has time for a call, it's the highlight of my week. I'm constantly learning things from him. Warren and I love to talk about companies, politics, world events, and new innovations. And it's really exciting to have somebody who's studying these things with a bit of a different background. He's got that economic investor's eye and I have much more of a technologist's eye towards things. As trustee of our foundation, Warren is an amazing thought partner to Melinda and me. When faced with a challenge, we often ask ourselves, "What would Warren do?" It usually leads us to the best answer. Warren and I are mostly peers, but sometimes he is so much wiser than I am, he's like a father figure to me.

Emotionally Invested: Warren earned a reputation as the "Oracle of Omaha" for his shrewd approach to investing in business. But he's equally gifted at investing in people. I'm always amazed how he is able to draw people in and make it fun for them to learn from him. Even though he keeps up a hectic schedule, Warren finds time to nurture friendships like few other people I know. He picks up the phone and calls to say hello. He regularly sends articles he's read in the mail that he thinks Melinda or I will find interesting.

I've learned many things from Warren over the last 25 years, but maybe the most important thing is what friendship is all about. It's about being the kind of friend you wish you had yourself. Everyone should be lucky enough to have a friend who is as thoughtful and kind as Warren. He goes out of his way to make people feel good about themselves and share his joy about life.

To this day, every time I go to Omaha (which I try to do whenever I can), Warren still drives out to the airport to pick me up.

It's a small gesture, but it means the world to me. I'm always impatient for the plane doors to open because I know Warren will be waiting with a new story or a joke and I'll be learning and laughing with him all over again.

Thanks for your friendship, Warren. It's been an amazing 25 years. I look forward to making many more memories with you in the years ahead.

Commentary by Bill Gates, the founder and former CEO of Microsoft. Today, Bill and wife Melinda co-chair the charitable foundation that bears their name and are working to give their wealth back to society. Follow him on Twitter @billgates.

See snapshots of Bill and Warren's 25-year friendship on Bill Gates' blog.

For more insight from CNBC contributors, follow @CNBCopinion on Twitter.

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