It was a lively trip in the Roadster. Frida had more than her ordinary jittery energy, tugging at her necklaces and offering a steady stream of half-invented history lessons mixed with urgent personal advice. “Sóli,” she declared suddenly, “I have to teach you to drive this car. César isn’t going to live forever. You know, I’ve been thinking maybe he died already. He’s been looking mummified all this year.”

The car was headed northwest at a fairly breakneck pace. The city’s outskirts trailed out into villages like the ones on the southern edge, tucked between lime orchards and stony stretches of desert. Hens picked through the roadside litter, and here and there a rooster stood in the center of the road with the authority of the police. Mangoes spread their leaves like umbrellas. The car shuddered when Frida abruptly veered to avoid a boy chasing an emaciated cow in the road. Mother’s death loomed large, an apparition.

“I’m serious,” Frida said, after relocating the road with the majority of the Roadster’s tires. “You have to learn to drive. I’m commanding you, as your boss.”

“Promoted! From secretarial assistant of the world’s leading political theorist, to Señora Rivera’s driver.”

“I’m trying to do you a favor. You could have more freedom.”

“A knowledge of driving, with no hope of ever owning a car. An interesting formulation of freedom. Maybe you should present a paper.”

“When did you become such a big sangrón? You used to be nice.”

She kept her mouth closed for several kilometers, which improved her driving. Running through the speeds in the Roadster with the gear-shifter on the floor looked simple, compared to the Model T with its hand-grip levers for running the accelerator and clutch. Even so, Frida grinds the gears like a butcher. The Chevrolet even has a gauge showing the gasoline level, so you don’t have to guess when it’s running out. Sometimes César forgets and lets the Model T run so low he has to back it up a hill, to drain out the last of the fuel from the tank under the seat. That would be Frida’s style as well.

Eventually she pulled over in a village, asked directions, and came back determined to get in on the passenger’s side. The driving lesson that followed was successful, until too successful.

“You can’t go this fast,” she admonished, though we moved at a fraction of her former speed. “You have to move the shifting thing across to the other side first.”

“We’re in the highest gear.”

“Well, you must not be doing it right. It’s supposed to make a sound when you put it into high.”

“Not if you double-punch the clutch. Watch this, you stop the shifter in neutral, that’s the cross-part of the H, and let the clutch all the way out, then put it back in again to match the gear speed.”

“Bastard. How did you know that?”

“I’ve spent a thousand hours in the car with César, trying to keep him from wandering off the end of the earth. I learned the gears. What else was there to do? Listen for the one-millionth time to the story of Pancho Villa in Sanborn’s?”

Frida laughed. “Poor old Cesár. Drinking a citrate of magnesia in the presence of Pancho Villa. And that’s the best war story he’ll ever have.”

“At least with his slow-motion driving you can see how everything works. He treats the transmission like a woman. He’d rather cut off his fingers than grind the gears the way you do, Frida.”

“Screw yourself.”

Pupil and teacher were relieved when the tops of the pyramids rose into sight, looming over the tile roofs and palm trees of San Juan Teotihuacán. The archaeological site was closed because of the excavations, and the crew had vacated for a long lunch. Their trowels and notebooks lay about every which way. While awaiting Gamio’s return, Frida decided to climb to the top of the Pyramid of the Sun, to get a perspective on the place. It took half an hour because of the steepness and number of steps: two hundred twenty-eight. She dragged her bad leg up every one, counting them with a hail of obscenities: cuarenta-y-dos-chingada, cuarenta-y-tres-chingada. Sometimes the steps were so steep she had to climb “on all four paws,” but she never accepted a hand. “I might be a damn cripple but I’m not dead yet,” she spat. “If my heart stops, fine, you can carry me back down.” Still angry from the driving lesson.

The view from the pinnacle could stop any heart: the complex geometric forms of the ancient city revealed themselves below, and beyond them, a landscape of black volcanic mountains. The pyramids of lava rock seemed to rise straight from the land, rather than having conquered it. And in fact, a half hour later when we stood on a platform in the ancient city’s central plaza looking back at the Pyramid of the Sun, you could plainly see what she called “the joke of the ancient guys.” The profile of the Sun Pyramid—its staircases, balustrades, and rounded top—perfectly follows the shape of the volcanic mountain rising behind it. A giant monument playing copycat to a mountain.

“They were laughing. The joke is on God,” she said, and sat down on the dusty plaza to make a sketch of the pyramid and mountain.

“If you say so. But it’s a joke with years of planning behind it, and terrible labors. Probably people died building it. Why throw away life to play a joke on God?”

She held a spare pencil in her mouth, and didn’t look up from her drawing.

When Dr. Gamio arrived, he had plenty of theories on the subject. The people wanted greatness. They worked hard to be remembered by eternity. Alignment was a sacred matter, as important as water and bread. He escorted Frida to the excavation site holding her arm, warning her against tripping over every pebble. His first words were to say how sorry he was that Diego couldn’t come, but he was not sorry. He was enamored of her, like everyone else.

The excavation lay open: a mass grave, protected under a temporary tin roof set on posts. Down a few dirt steps, there they were, skeletons of men lying in a row like fish in a box, their narrow, dust-colored bones only faintly lighter than the reddish dirt in which they were embedded. Oddly, the skeletons were perfectly flattened, as if all these humans had been pressed under a hot iron. It took a moment for the eye to adjust to the increments of dust, discerning the human from nonhuman elements. The dead wore jewelry that had survived where flesh did not, bracelets loosely encircling bones. Most peculiar of all: around each neck, a sort of cravat or necklace made of human lower jaws, with the teeth still in place! It was a riveting sight, these bizarre, scalloped strands of mandibles strung together, looping low across the former chests, a fashion beyond anything even Frida might wear. The professor pointed out cut marks here and there on the bones, butchery marks, which he claimed as proof that these unfortunates were sacrificed.