refurbished when Sun Line took over in 1973 and several times after that, the vessel offered all the charms of a vintage ocean liner, not least of which were its sleek lines and cascade of open deck that clearly predate the chunky, veranda-laden cruise ships of the nineties. For most of us the point of this journey was to taste of the Maya world—and in a short time only a taste was possible—but three full days at sea on the schedule also promised the chance simply to relax. From the start, when a synchronized trio of leaping dolphins followed the vessel out of Galveston Harbor, to a series of flamboyant tropical sunsets, and through to the evening of Greek entertainment when the captain joined in his crew’s spirited singing and dancing, shipboard life met all the promise of a glossy color brochure.

The first port of call, the island of Cozumel, lies just off the Yucatán Peninsula. There, passengers could choose from several tours, among them a trip around the island, stopping at San Gervasio, where the remains of a city dating from A.D. 300 to 1500 are set amid blessedly shady vegetation, providing a pleasant and manageable first look at the stubbornly secret Maya world. Our guide, Joaquín, claimed, as most guides in the region do, Maya ancestry. “Erase in your mind for a few minutes,” Joaquín said, “the idea of ‘Indian,’” and he went on to count his forebears’ achievements—the art, architecture, calendar, mathematics, and the ancient, hieroglyphic language that today’s Mayas neither read nor speak. The original names of the gods to which San Gervasio’s buildings were dedicated are gone; the precise purposes of these structures are only guessed at, “but they knew, amigos,” Joaquín whispered, “they knew.”

San Gervasio was only the warm-up for the main event, a visit to the former city of Chichén Itzá, one of the largest, most combed-over, and probably the best-preserved of all Mesoamerican ruins. Founded around A.D. 450, in the early classic period of Maya history, Chichén, as our team of scholars called it, gained new strength in the eleventh century, when, it is thought, the Toltec peoples of central Mexico moved into the region, leaving their stamp on the architecture here. The Spanish invaders of the 1500s came, even as we do now, to marvel at the scale and audacity of Chichén’s structures and to absorb the elusive sense, of which Joaquín spoke, that what “they knew” we still do not.

We are at Chichén on the 21st of March, a Mexican national holiday (marking the birthday of Benito Juárez), one day after the official equinox, to join with thousands of Maya and other Mexicans in witnessing a kind of light show, a natural phenomenon that has taken place every spring and fall for centuries. When the late-afternoon sun shines onto the stepped north face of the pyramid-shaped main building, the Castillo, it casts a light that takes the shape of

seven triangles. As the sun sets, these triangles gradually descend the building to create, in the space of an hour or so, the illusion that an outsize diamondback rattler is gliding down the stairs, an image made even more powerful when the lowering sun finally reaches the great carved snake’s head resting on the ground. Was this effect intentional or just an extraordinary trick of the light? Despite recent breakthroughs in understanding the Maya culture that have followed upon the first decoding of the written language, no one knows for sure. It may have been a way of honoring a local god called Kukulcán, a feathered serpent, who may in turn have represented renewal. As the snake sheds its skin, so we all mark the movement of time, reinforcing an age-old awe for what Ed Krupp calls “the mystery of order and change.”

For those who continue to try to pin down the meaning of this pageant of light, Krupp offers his three archeologist’s rules: (1) yes, it does mean something; (2) people do things for reasons; (3) it’s always more complicated than you think.

Despite the air-conditioned buses, the ample hotel lunch along the way, and the constant flow of ice water and juice offered by the Stella Solaris staff, there’s no denying that this is a demanding day. Not one, of course, to be compared in any way with the hardships endured by earlier generations of explorers, but it takes its toll. After three hours on the bus, and another three or so of wandering broad, shadeless courts, I find the fantastical carved limestone temples, baths, and ball courts seeming to shimmer in the broiling heat. Some of us simply fold up on the only available seating, a bed of roots and rocks and dust, feet refusing to travel as far as the mind will go. The crowds that day were estimated at about 30,000, and most of these were young—a new generation of Maya. There were masked dancers, drumrolls, and political harangues (some, I was told, referring to the recent events in Chiapas). To the growing anticipation was added a sense of unease when, as the day wore on, clouds gathered, threatening to obscure the sight of the descending snake. But then, somewhere around 5:00, as we sat facing the Castillo, the sun pierced a bank of clouds, and one more time in its centuries-old slither, the serpent returned. A moment of unified silence was followed by cheers.

The next day, back on the ship, our lecturers asked for a vote: Who would have preferred to visit Chichén Itzá on March 20, the actual day of equinox, when relative calm prevailed and the snake’s audience would have numbered about 1000? And who would choose to go back all over again to join, as the astronomer Anthony Aveni put it, the tumult of “30,000 people getting in touch with the universe”? The final tally favored the universe by a margin of two to one.