“Visible things pass away; invisible things do not pass away.” The priest expressed this principle with a certain detachment, as if he were lecturing in a metaphysics course. After the homily, Henri, a Jesuit in formation who likes to describe himself as “half-French,” shifted towards me and whispered that they had arrived. We stayed for the consecration. As we shuffled out of the narrow pew, no one in the congregation showed any sign of registering our abrupt departure from Mass. Outside it was so bright that I could only see what was on the other side of the open door by passing into the light.

It was a Friday in June, and Henri and I had just finished another year of philosophy studies in the Midwest. As Jesuits in formation we are sent each summer to a new location to do work with a local community. Our original plan was to help lead some parish summer camps in Belize, but when that idea became impractical, we were sent to San Diego. Shortly after we arrived in California, Rob, a Jesuit from the West Province, invited us to spend a weekend with a volunteer search and rescue group in the Sonoran Desert of southern Arizona. The Armadillos, as this group is called, is one of about a dozen. Its members hike through the desert border region searching for migrants—dead or alive—who have attempted the perilous crossing. Rob had been on many of these missions before, but never with the Armadillos. He was not sure exactly what to expect.

Our rendezvous point in San Diego before we drove to Arizona was the basilica of San Diego de Alcalá, one of the first missions that St. Junípero Serra founded in Alta California. After we left the Mass, Henri and I walked in the shade along the wooden veranda. The summer solstice was approaching and the evening sun still hung high in that perfect sky; the palm trees and three-tiered bell tower of the mission shone with a golden luster. In front of the bleach white walls was a white pick-up truck decaled with Armadillos: Busqueda y Rescate. We found Rob waiting for us behind the truck and chatting with two Latino men. Rogelio was in his early fifties, short and thin, clean shaven and gray-haired. He was the leader of the expedition. He possessed a quiet authority, and I trusted him immediately. Armando was a bit younger, about the same height but stouter, with a thin mustache that added some playfulness to his face. Any doubt of their physical capacity to complete this mission evaporated when I shook their calloused hands. I understood that I could not acquire their kind of strength from the gym.

We drove east from San Diego on I-8 and waited at a gas station on the outskirts of the city to rendezvous with three other members of the expedition. Reynaldo, Pablo, and Mateo soon pulled up in a black van. The red lettering on the side of the van read, “Giving dignity to the migrant.” I asked Reynaldo how many of these search and rescue missions he had completed. He shrugged. “I don’t know; too many to count.” The A.C. in the white pick-up was not working, so I hopped into the black van before we continued east. The men spoke sparingly. I felt the pressure increase in my ears as the van ascended into the dusty mountains. The sun set behind us. In Yuma, we rested at a Love’s gas station. Reynaldo took out a bag of homemade burritos wrapped in tin foil and filled with eggs. He warned us with a mischievous smile that he had added some habaneros for spice. Mateo afterward poured some chocolate covered coffee beans into my hand, which kept me alert for the next few hours. Rob expressed some concern about the obviously deflated front left tire of the black van. Mateo bent down to look at it, and after a few moments of contemplation, grinned: “It’s fine.”

It was late in the night and long into the journey when we stopped again. My van suddenly pulled off onto an abandoned dirt road and parked next to a wooden shed. While we waited, I wondered if people were kidnapped on this side of the border. There must have been some confusion because my group called Rogelio to find out his location. We reconvened at a gas station in Gila Bend. There we met up with José, another Armadillo who had driven down from Phoenix. As we stood outside under the bright lights of the station’s pavilion, Henri and I locked eyes and laughed nervously. I was grateful when Pablo filled the flat tire with air.

With the caravan now complete, we continued south to Ajo and turned down a dirt road into Organ Pipe Cactus National Monument. Clouds of dust stirred up by the white pick-up truck in front of us obscured the headlights and forced us to slow down on the sharp turns. In the dark, the headlights illuminated a large brown sign that read, “TRAVEL CAUTION: Smuggling and illegal immigration may be encountered in this area—Avoid traveling at night.” Later we passed an unfamiliar truck on the side of the road. Reynaldo pointed and whispered: “Drugas.” Finally, after almost an hour, the caravan arrived at Bates Well, a cattle ranch camp built in the early twentieth century. There was a dilapidated but still intact bunk house and a motionless weather vane. We unloaded our bags and set up camp on the flat ground enclosed by a log fence. The Armadillos offered us a casita (a tent), but we chose to sleep under the stars.

As I lay on my sleeping mat, I heard the grinding drone of jet engines from the nearby military bombing range and then what sounded like the rapid dull thumps of munitions in the distance. It turned out to be a Border Patrol truck searching the desert for migrants traveling under cover of darkness. I fell asleep below the twinkling stars. I soon woke up to Henri shivering next to me on the tarp. I was shivering too. The temperature had dropped significantly in the night. I thought about draping my thin sheet over Henri, but the threat of the cold beat out my charitable impulse. We did not suffer for long since we soon heard Rogelio’s voice calling us out of bed.

It was still pitch black when we broke camp and piled into the white pick-up truck. I was grateful that I sat between Reynaldo and Pablo in the truck bed; driving on that road felt like riding a mechanical bull. The rising sun gradually revealed our surroundings. The landscape lay before me as in a dream. Organ Pipe is true desert. Twenty- and thirty-foot cacti that I had only seen depicted in cartoons and Westerns towered over the martian landscape. Brown, barren mountains with names such as Titanic, Scarface, and Llorarás (“You will cry”) encircled us and were presently blanketed in a patchwork of sun and shadow. The only signs of animal life were the buzzards that hovered above us like black kites bouncing in the breeze.

Before we left San Diego, Rob had debriefed us about the expedition. The Armadillos were searching for two migrants who had disappeared in this area a few years ago. It was not an uncommon occurrence. Thousands of migrants have gone missing while crossing the border from Mexico into the United States. Many of them disappeared in Organ Pipe Cactus, which is one of the cheapest—and most dangerous—smuggling routes along the border. Sneaking past the border fence is just the beginning. Migrants still need to cross more than fifty miles of desert, numerous mountain ranges, and a bombing range until they reach I-8. The trip can take up to two weeks, and they need to carry enough food and water for the whole journey. The Armadillos travel here each month to investigate a different pass between the mountains.

We formed a search line with thirty or forty yards of separation between each of us to cover maximum ground. I was handed a green walkie-talkie and told to call if I found anything. The topography of the landscape varied. Sometimes it was flat, sandy soil covered in brush. Other times it was scarred with steep ditches populated by plants wielding needles, spikes, thorns. Generally, the tall cacti were easy to avoid; you really had to be worried about the chollas. These cacti propagate by dropping clumps of barbs that latch onto anything unfortunate enough to contact them. At one point I was clambering out of a ditch and felt a sharp pain on the back of my left thigh. I looked down and found a cholla there to greet me. Every so often one of the Armadillos would call from down the line and warn us to watch out for rattlesnakes. Under my pack I felt like one of the now-long-gone range cattle lumbering across the desert scrub with its swaying head hopelessly scanning the ground.

At first, I did not believe that we would find anything. The desert was too inhospitable; no one would dare make this journey. To my horror, I soon found signs of life everywhere. We were on a highway through the desert. Shoes, clothing, hats, aluminum cans, and plastic littered the landscape. Frequently I found torn carpeting buried in the ground, which migrants wear on their shoes to avoid leaving tracks that could be traced by Border Patrol. We found many black water jugs tied together by frayed rope. Migrants sling these around their shoulders for the journey. The identical jugs indicated to me that the same smugglers were responsible for transporting all these people. Every so often there was an article of clothing on the ground that looked fresh, like it had been dropped yesterday.

In three hours we arrived at a mountain that resembled a human molar. Kino Peak was named after the seventeenth-century Jesuit Father Eusebio Kino, who founded a series of missions in this region. We stopped for lunch. The Armadillos seemed to have an inexhaustible supply of burritos. I collapsed from exhaustion. José fell asleep on the dry ground, and Rob muttered, “El sueño de los justos.” When the Armadillos asked how I was doing, I must have sounded unconvincing. Rogelio turned around and uttered a single word: “Bautizo.”

After lunch we began our ascent up the mountain, gradually forming a single-file line as the valley narrowed and the slope steepened. I climbed hunched over for a low center of gravity so that my hiking bag would not drag me backward. Eight hundred feet of elevation later we rested at the top and snuggled into the crevices between the rocks to hide from the scorching sun. Nec est quod abscondatur a calore eius. I found rusted aluminum cans nestled in the rocks. Rob pointed to a plastic tarp from where a halcón—a cartel lookout—would have monitored the valley below. Our descent was more difficult than the ascent. We split into two groups of four, hugging the sides of the canyon like long-horned ibex. I began to feel a strain in my knees and ankles as every step involved a careful discernment of whether the rock below me would support my weight or give way. Eventually we reached level ground and began making our way through a broadening valley that was just as desolate as the one before.

There was something different about this valley. The banter on the walkie-talkies died down noticeably.

“Tom, I smell something bad,” Rogelio called out to me. “It could be a body. Be careful.”

As we combed the desert floor, I asked José how he became one of the Armadillos. He paused, searching for the right words. “Humans . . .” He lowered his head. “Humans can be animals to each other.”

When Henri’s walkie-talkie died, he followed me for safety.

“Henri,” I asked, “is there a little part deep inside of you hoping that we find a body?”

“Yes, I guess so,” he said. “What about you?”

An answer was not necessary. We heard Reynaldo’s voice over the walkie-talkie: “Ropa y huesos.” We backtracked and found Reynaldo standing over an unusually large pile of clothes in a shallow trench. The bones were nearby. There was a tibia, and then from a few paces away I heard Reynaldo say “costillas”—ribs. I had seen human bones before in catacombs—heaps of skulls and femurs filling dank vaults—but never like this. The whiteness of the bones made me uneasy; the sun had bleached them to look unreal. Rogelio called in the other group over the walkie-talkie and began to scout the area for other remains. Of course we did not disturb anything. We took pictures, recorded G.P.S. coordinates, and made a report to Border Patrol, who would send a sheriff and a medical examiner to identify and collect the bones. I saw Henri cautiously pace around the area tying pieces of orange tape around branches to mark the location of bone fragments scattered by coyotes and buzzards. When a bone was not near a bush, he would tie tape to a stick and support it between a pile of rocks.

A silence came over the group as we searched the area; the only words exchanged were to alert others to more remains or clothing. Not long afterward we gathered around the tibia—the largest bone discovered—for a prayer. I volunteered to lead, and we bowed our heads. As I spoke I realized that I was not quite conscious of the words coming out of my mouth. The ones I heard myself saying seemed awkward and unsuitable; I thought that when I finished and opened my eyes I would encounter a circle of angry and disappointed faces. The Resurrection seemed far away from these dry bones. I was surprised because I could not quite muster up belief in that moment. I prayed from a void.

“Are not two sparrows sold for a farthing? And not one of them shall fall on the ground without your Father.” This happened to be the Gospel for the next day, a Sunday. Whoever these bones belonged to fell to the ground to die lonely and abandoned. What had made this crossing seem appealing enough to prompt the attempt? Was it the dire conditions in the place of origin or the perceived promises waiting on the other side of the desert? Or perhaps they were misled by the smugglers about the difficulty of the journey? In either case, what solace was God’s knowledge as the hope of rescue slipped away with the descent into unconsciousness? Jesus told His disciples not to fear. But as the reality of impending death settled in, what had this person felt?

Rogelio added a few words after my prayer: “I know this is difficult work, but it is worthwhile.” You are worth more than many sparrows. Dignity. It is a word that I thought I understood before this hike. As I gazed down on the bones, I realized that the men standing beside me had a deeper and more intimate knowledge of human dignity than I did. Dignity was an invisible reality that would not pass away. One day I knew that those very bones would be linked back together, filled with marrow, strengthened by tendons and ligaments, and covered with skin. Breath would fill the lungs again. It would be physically alive, but not like before. This body would be a new creation present in a radically different dimension of existence. These dry bones would one day rise again. I recalled the Spirit descending on the pale, dry bread in the Mass at the mission church and filling it with life. How? Lord, You alone know.

After ten hours of hiking, Henri and I were up against our physical limit and out of water. So it was fortuitous that after passing through a desert wash we finally intersected with one of those winding dirt roads. Mateo was waiting for us there in the white pick-up truck. He handed us water and Gatorade from a small cooler. I sprawled belly up in the bed of the truck on top of our hiking bags. On our short ride back to Bates Well, Rogelio told me that the Armadillos usually spend another night out in the desert but were returning early because of Father’s Day weekend. In Gila Bend, the caravan stopped for dinner, where I watched with a mixture of disgust and admiration as José devoured another burrito.

✥ ✥ ✥

A few days later Rob, Henri, and I were walking through downtown San Diego. It was another perfect day in the California sun. I asked Rob about the status of our report to Border Patrol. He paused for a moment like he was considering how to deliver news of a chronic diagnosis. At last he said, “Yes, I received a response.” He paused again. “The medical examiner told me that the remains were not human bones. I’m surprised. There was a lot of clothing. And I could swear that tibia was human sized.” I didn’t dare ask how many tibia he had seen before.

I reflected on this news as we continued home. I found myself gazing on the broken, withered bodies of the people living on the streets. Some were emaciated and others were swollen. Some had fractured limbs and were limping in boots or rolling themselves along in wheelchairs. A few were even sprawled unconscious on the ground. Everyone seemed dried out. And I couldn’t stop thinking about those bones in the desert. Even if they were not human after all, they had helped make a fact of human existence a little less abstract. I saw everyone differently. The bright sun set them aglow. Amid these broken bodies on the street, I knew that these bones—theirs and mine—would live again.

“Hey, pastors!” A woman sitting in a walker had noticed our Roman collars. “Can you give us a blessing?” She indicated to the motley group standing around her on the sidewalk. I turned to her and stepped into the sunlight.