He left photography to become a doctor. Could he go back?

I stopped receiving calls on my cell phone while I was training to be a doctor. My friends knew better. My life was not my own. As a resident I sometimes worked nearly a hundred hours a week, overseeing as many as 18 patients at once. Even my mom stopped calling me. I used my phone instead for medical apps—the one that could tell me which antibiotic to prescribe for which bug, the calculator that helped me determine treatments, the app that stored lab values I couldn’t remember.

Then one day my cell phone rang. I was on rounds seeing patients and stepped out to the hall. I didn’t recognize the number, but the area code was Washington, D.C. This call, I thought, must be important. “Yes?” I whispered in the hallway.

“Hey, Max,” the voice boomed. “It’s Todd.” Todd James is a photo editor at National Geographic. I hadn’t spoken to him in 10 years, certainly not since I’d left photography to become a doctor, but I recognized his Oklahoma twang. “I’ve got a job for you.”

The story was on stem cell research, and he wanted to send me all over the world to shoot it. As Todd talked, my mind reeled—yeah, that was the life, on the road with my camera, with license to explore. Being a photojournalist is like being Zelig, or Forrest Gump, or Walter Mitty: You aren’t the important one, but you’re right there with whoever or whatever is. I’d been a photographer for 20 years, but I stopped when I realized I didn’t want to be the voyeur anymore. I wanted to be having the experience myself.

I’d found a new path when I was assigned to photograph a neurosurgeon performing a spine procedure. The patient was upright, his skull locked in something like a C-clamp, his spinal column stretched out, which allowed the surgeon to operate standing and at eye level, with clear and clean access. At one point she said, “Here, take a picture of this.” There before me was the exposed spinal cord, pristine and white. I realized this thing had never seen light, wasn’t meant to see light, and at that moment was bathed in light. I was in awe, as if I’d awoken to find myself in a flight suit on an Apollo spacecraft, heading to the moon. I knew right then that this was where I wanted to spend the rest of my life. I contacted all the magazines I worked for and asked them to give me all their assignments on medicine and doctors. About 10 surgeries later I thought, I could become a doctor myself.

“I don’t know,” I told Todd. “I’ve got patients I’ve got to see right now. I’ll call you back.” So there I was, finishing rounds, seeing patients, writing notes, being a doctor, totally conflicted. The itch I’d scratched for so many years was still there—that itch of seeing the world; making decisions about color, about light, about what to leave in the frame and what to leave out, about how to tell a story; and the pure joy of looking through a lens. That afternoon I ran into the assistant director of my residency program. He pointed out that I had an elective month coming up. I had the option to spend it doing research. “This story. It’s research, right?”

I called Todd right away. He figured I could do the story in 23 days—13 shoots in 13 countries. The first would be in my own hospital, UMass Memorial Medical Center, where there was a clinical trial using stem cells to treat lupus. From there I headed to Europe.

In Berlin I went to the former lab of Rudolf Virchow, the 19th-century doctor who had established that all cells are created by the division of preexisting cells. I wanted to create a picture that illustrated the power of a pluripotent stem cell. By stacking pathological specimens, I made an abstract human: hair from the head of a stillborn infant, a brain, an enlarged heart, a liver, bones, and teeth—all parts of us that could come from a single stem cell.

I’d forgotten how to use a light meter, but the rest came flooding back. Being a photographer is serious business, but I had 20 years of experience doing it. So many things had gone wrong in so many different situations with so many different people that I had figured it out. I was a master. Shortly afterward I began my first rotation in the intensive care unit, aware that it would take 20 more years before I had the mastery I needed—and wanted—to have as a doctor.

A year later, as a resident guiding my own interns, I wondered what to specialize in. Then I knew. I wanted to make photographs again, I wanted to make films, I wanted to tell stories like nothing else mattered. I was leaving medicine—but with hard-won scientific knowledge and experience caring for the ill, a graduate degree in the human condition. I’d received a call I had to answer, the call to create.