The true measure of a man is not his physical size but the good deeds and special memories he leaves behind. While Don Keough was a man large of stature, his real measure can be seen in his family, friends, colleagues and institutions he touched during his 88 years of life.

When he passed away last week, Atlanta and the world lost one of its most dynamic and charismatic business, civic, education and philanthropic leaders. The loss to me was personal because I was honored to call him not only a longtime business partner but also a dear longtime friend, advisor and mentor. The Coca-Cola Company, its worldwide system of bottlers, partners, employees and customers, the soft drink industry, Allen and Company, Berkshire Hathaway, IAC/InterActiveCorp, Yankee Global Enterprises and civic organizations lost a strong, guiding light.

Don entered the business world after a brief sojourn in television, working alongside a young comedian, Johnny Carson. He later joined an Omaha wholesale grocery company that had several brands of coffee. The company was later acquired by The Coca-Cola Company. Thereafter, for more than a half century, Don Keough was associated with Coca-Cola. During those years, he brought a steady hand to the wheel in good times and in challenging times.

He was a leader who understood that companies are not living, breathing entities but are the product and extension of the personal characteristics of its leaders and the people who work there. In his New York Times best-selling book “The Ten Commandments for Business Failure,” Don quoted the anonymous sage who said, “Managers are concerned with doing things right. Leaders are concerned with doing the right things.”

Don Keough personified doing the right things. Where Coca-Cola was concerned, he understood that it was more than just a product; it and the other brands were a trust and a legacy – assets beyond value and the keys to our future.

He once told me he had a simple view of his job: “Every day I come in, I want to polish our brand – make it shine just a little brighter, sparkle just a little bit more.”

No matter where I am in the world, those words are watchwords for me.

Speaking years ago to company advertising executives, Don defined in explicitly simple terms the role he had as president of The Coca-Cola Company: “I define my role as: to protect and enhance the trademarks of the company. That’s all we do. That’s all we should do.”

Don was a rare combination. He understood the world and people in it with both his head and his heart. He had a genuine love of people and he celebrated those things that make each of us unique. He had a need to understand the differences in people and to learn from every one of them.

As a man who lived for the details, he had a driving curiosity for how things worked and an unrelenting determination to make them work better. To my mind, no one has ever known more about the Coca-Cola business. He also knew that a business, any business, does not succeed merely on the excellence of its brands and its mechanics. A business succeeds because of its people – the bonds they form, the relationships they build and the vision they share.

The strength of his leadership was formed because he was a consummate relationship builder. That signature skill came as naturally to him as breathing. He adored people. He could relate to anyone, regardless of culture, background, walk of life or age. Across 140 countries and countless lunch and breakfast tables, he demonstrated that quality with rank-and-file Coca-Cola employees, customers, world and local leaders. Every encounter with another human being he saw as a learning opportunity.

One of the rare traits Don possessed was that he was always constructively discontent. He adopted Oscar Wilde’s mantra, “The world belongs to the discontented.” He believed that occasional failure was the price of progress. On many occasions, he said that the word “success” made him nervous, because, “I believe built into that word are a couple of viruses – arrogance and complacency – and left unchecked, they can ensure failure.”

I’ll always remember his routinely asking the question, “Isn’t there something we should be worrying about today in order to make sure we have something else to worry about tomorrow?” Don regularly reminded his colleagues that, “Success is a journey and not a destination.”

In recent days, many have written about the famous Coca-Cola Classic news conference when Don announced the consumers had won and that “old Coke” was being brought back. He noted that some cynics speculated that the New Coke introduction has been a marketing ploy. Don famously responded, “The truth is, we’re not that dumb, and we’re not that smart.”

Just a couple of years ago, Don shared his lifelong passion for learning with the first class of a Coca-Cola leadership program named in his honor. “The brain is like a sponge,” he said. “If you let it get dry, you can peel it off bit-by-bit. That’s the way the brain is. To have output, you have to have constant stimulus and input – knowledge dripping in every day to keep the sponge-like brain moist and viable.”

Many things have been written and said about Don Keough’s legacy, which will long endure not only at The Coca-Cola Company but also at Allen & Company, where he served as chairman since 1993. He also made a lasting and positive difference serving on the boards of many other organizations including Coca-Cola Enterprises, Columbia Pictures, McDonald’s Corporation, The Washington Post Company, H. J. Heinz Company and The Home Depot.

Our heartfelt condolences go out to the Keough family that Don loved so much. We share their loss, and we share their pride in the legacy of one of the truly great leaders in the history of business.

The world has lost a giant of a man in Don Keough, and we at Coca-Cola have lost an extraordinary leader, mentor and friend. As much as we will miss him, we will forever hold fast to the lessons he taught us about working and living with passion and a genuine love for others.

Muhtar Kent is Chairman and CEO of The Coca-Cola Company.