When I found out yesterday morning that Paul Farmer had died, I thought first of his wife, Didi, and their three children. I thought of his colleagues, and of everyone whose life was saved or changed for the better by him. And then I thought of all the people who know and care about global health because of Paul, far too many to count.

Paul is a hero, and I was fortunate to call him a friend. Although we crossed paths at various conferences over the years, the first time I really got to hang out with him was during a trip to Cange, a small town in central Haiti, with Melinda in 2005. We were there to visit a health clinic run by Partners in Health, the incredible organization that Paul co-founded (and that our foundation is proud to support). At the time, PIH was providing world-class healthcare to people in Haiti, Peru, and Russia, although it’s since expanded to eight more countries.

I’ve visited a lot of rural health clinics through my work with the foundation. I’m always blown away by the remarkable and dedicated people working at them, but Paul was special even among such peers.

He was able to connect with his patients in a way that would be exceptional for any doctor, but was especially so for a gangly white guy from the Berkshires working in rural Haiti. He was a teacher who loved educating his students, whether they were future doctors studying at Harvard Medical School or community health workers-in-training at one of PIH’s clinics. But the thing that always stood out to me most about Paul was his single-minded focus on helping people in the world’s poorest countries.

In Tracy Kidder’s book Mountains Beyond Mountains—which I can’t recommend highly enough if you want to learn more about Paul’s career—there’s a story about a young child whom Paul and his team treated for drug-resistant tuberculosis in Peru. After the boy was discharged from the hospital, his mother approached Paul to thank him as he was getting into his car to head home. Paul responded in Spanish, “For me, it is a privilege.”

He was never happier than when he was caring for patients in one of the clinics he helped create. I have never known anyone who was more passionate about reducing the world’s worst inequities in health—or who did more to live by his values.

Even as Paul’s reputation as a global health hero grew, his focus never wavered from helping people directly on the ground. He was a humble man who never had any interest in seeking attention unless it would make life better for the people he served. I remember meeting with one of his patients during that first visit to Haiti. The woman spoke Creole, so Paul had to translate for us. At one point, she launched into what was clearly a long story about him—I could hear the words “Doktè Paul” mentioned several times. When she finished, I turned to Paul and asked what she had said. He sheepishly replied, “Just some obligatory praise for me.”

The only time Paul sought the spotlight was when he knew he had an opportunity to highlight inequality and speak to the next generation of global health leaders. He gave many commencement addresses over the years, and I suspect he’s the reason a lot of young people have entered careers in public health. He is one of the most inspirational people I’ve ever met. His ability to inspire was one of the reasons why, when Melinda and I went back to visit Paul in Haiti in 2014, we brought our children with us.

Although his work was his life’s joy, he was a wonderful person to be around when he was off the clock, too. I have fond memories of visiting his modest house in Haiti, which had a lovely garden that he was proud of. One of my favorite Paul stories happened when I traveled to visit PIH’s facilities in Rwanda. After our meetings were done, we decided to visit the mountains nearby to see the gorillas—but Paul hadn’t brought a change of clothes with him. I’ll never forget the image of Paul trekking up the steep misty hillside wearing a suit and tie.

There will never be another Paul Farmer, and I will miss him deeply. I am comforted by the knowledge that his influence will be felt for decades to come. His work will continue through Partners in Health, and it will be carried on by the many people he trained and inspired.

At the end of the day, though, Paul’s most lasting impact can be found in the patients he loved so dearly—all of the mothers, fathers, sons, and daughters who are alive today because Paul dedicated his life to helping them.

I can’t imagine a more phenomenal legacy.

This article originally appeared in The Atlantic.