PALACIOS, BOLIVIA — Beneath the breast bone, between the lungs, lies the heart. It is a fist-sized organ, the color of uncooked steak. It was extraordinary, as a child, to hear it beat: a stethoscope pressed between the shoulder blades, two fingers against the wrist. But how unextraordinary it became later, when I learned that 72 times a minute, it contracts at a signal from the sinoatrial node, pumping blood to the lungs then the arteries.

Education is meant to increase one’s appreciation, but in this case, it had the opposite effect. I could not marvel at the heart, knowing the trick to its beating.

The same was true of Yale. The first time I walked beneath Phelps Gate, I was in awe at the upperclassmen, banging upturned pots with wooden spoons. Like many of my classmates, I spent freshman year, looking up at the iron gates and fluted towers, the brick facades and green shutters.

In the years that followed, I found new sources of wonder: the warehouses in Science Park with the windows punched out, the wings of the stone angels, rising above the tall walls of Grove Street Cemetery.

But by senior year, I knew the magnolias to climb and the gardens to trespass. I had swapped spit, leaning from my bedroom window and fallen asleep, writing a paper in the newspaper room. Everything I expected; nothing was extraordinary.

It was then that I decided to spend the year after graduation, working at a free clinic in Bolivia. This confused everyone, because as a history major in the writing concentration, I had only ever expressed a writerly interest in the human body. But I took the job for that reason: It would be so terrifyingly different that it would never seem unextraordinary.

In August, I landed in Santa Cruz de la Sierra, a large but squat metropolis, whose architecture might have been inspired by sprawling car lots. Instead of skyscrapers, however, it boasts statues of the Lord Jesus, his arms lifted in triumph, as if he had scored a touchdown.

From Santa Cruz, I drove to the clinic. On the way, the billboards became less frequent, the towns more neglected, and after an hour, the paved highway turned to dirt road, and on either side, were sugar cane fields, burning. The clinic sits at the entrance to a land preserve, and concealed behind the jungle trees, it appears suddenly — in white and antiseptic brilliance.

At the clinic, I schedule appointments and answer calls; I drive patients to the city hospital and drive them back; I order the metal rods for the surgeons to insert in scoliotic backs. Even these errands seem extraordinary.

So do the patients who came to the clinic: a woman with a benign mass that pulsed; an agricultor who survived pneumonia and tuberculosis to tend the cows again; a man whose width was so extreme that he broke the examining table, but whose good humor was so great that he righted himself with a laugh.

At the end of my first month here, I took three women, three generations of a family, to the hospital in Yapacani, a town thirty kilometers to the west. The youngest had skin scabbed from chicken pox; the mother was malnourished and rheumatic; but it was the grandmother whom the triage nurse rushed to the emergency room.

She had Chagas disease — an infection, transmitted by the protozoan parasite Trypanosoma cruzi, that inflates the heart to twice its normal size. “Your heart should be the size of your fist,” an American doctor explained to me once. “Now, imagine two fists.” He held up his hands, like a boxer.

When the doctor emerged from the exam room, he did not mention bradyarrhythmias or thromboembolism — words that I had come to associate with Chagas. He said, “Cáncer.”

The nurses became too prim, the wards too white. All I could think of was the grandmother’s heart. I imagined it to have the dimensions of a football. Mine, on the other hand, was the size of my fist. I curled my fingers. How extraordinary, I thought, for it to beat 72 times a minute.

I had taken it for granted, as I had taken Yale for granted. Yet one must take the heart for granted, so as not to worry, 72 times a minute, that it will stop.

What is worse is to ignore the extraordinary in the routine — for it is not newness that makes a place extraordinary; it is the place itself. The magnolias and the gardens. The space outside the bedroom window. Being stirred awake, 15 before midnight, in a room full of newspapers.