As the world shifts and churns the only certainty is that we're all on the move. Ruben Martinez, an associate editor at Pacific News Service, has been taking lessons on how to survive from "illegals" on both sides of the U.S.-Mexican border. Martinez is at work on a book about life and death in the borderlands for Metropolitan/Holt.

CHERAN, MEXICO -- We live in the Age of Migration -- the only thing that's certain is that we're all on the move. I've been taking lessons in moving from some of the people who do a lot -- the "illegals."

Right now, most of the migrants I know are in their "first home," Cheran, an Indian village in the highlands of Michoacan, in Mexico. Every spring, about one-third of the people in the town head north for seasonal work in the United States. Every winter they return in time for the fiesta for Saint Francis, Cheran's patron saint, and other year-end holidays.

This is migrant Lesson Number One. No matter how far you go looking for the "better life," you have to return home at year's end. Home is all-important to a migrant. Without it, the journey becomes meaningless.

Winter in Cheran, as in much of the world, is a time to be among family, relax, take stock and envision the new year. Because this is an Indian village in a changing world, the holidays take on even greater significance. Because migration often separates families, it is a time of poignant, and sometimes troubled, re-encounters. Husbands and wives, parents and children, meet again. Best buddies -- who separated at the border seven months ago and gave each other up for dead -- join in tearful, drunken embraces. Teenagers come home to find a grandparent or an uncle in the grave, a father sees his newborn child for the first time.

The migrants come home with tales of triumph. Countless times I've heard a migrant tell how, after suffering a boss's abuse day in and day out through a season, he finally stands up and floors the gringo boss with one good punch -- after, of course, delivering a magnificent speech, in which he stands up for the dignity of all Mexican migrants everywhere and insults the boss's mother in a dozen ways.

That's another lesson: it's healthy to take pride in your journey, even to exaggerate. This contributes to the town's mythology, a reservoir of hope you can draw on when you go to try your luck in the north again. Hope is the salve on the wounds of a year's worth of fear and frustration, of nights spent on the floor of an apartment in a terribly fallen part of some big city.

You come back for the fiesta, to your family and your town and your country so they might know you took the best shots America could give and not only did you survive, you brought back some greenbacks and some shoes for your mother and a gold chain around your neck to prove that you did more than survive, you moved toward the future.

The future certainly holds ever-more movement, but this doesn't mean the people of Cheran abandon their past. During the fiesta, pine-needle wreaths and corn stalks decorate the church and Indian women bring baskets brimming with fruit as an offering to the Christ-child, melding pre-Columbian traditions with Christianity. Teenagers fresh from the States wearing hip hop regalia and bantering in their Indian tongue, Spanish, and English help harvest corn with tools used a thousand years ago: hands and straw baskets.

The migrants of Cheran have discovered America in Carolina tobacco fields and California citrus groves, in Missouri's greenhouse nurseries and Arkansas tomato farms. But migration is, after all, a two-way affair, and though it might be hard to detect at first, the Mexican presence in the U.S. is having its impact -- sometimes in the most intimate way possible.

Last Spring, visiting a small Wisconsin town, the destination of many migrants from Cheran, I found several dozen "interracial" couples. The local girls are learning Spanish and picking up a liking for norteno music; the Mexican boys learn English and walk down Main Street with heavy metal buzzing in their Walkman headphones. The first "mixed race" babies have appeared, some of them sandy-haired and golden-skinned kids.

Back in Cheran, after the last fiesta, the migrants turn northward again. They know -- from CNN en espanol captured on the town's dozens of satellite dishes -- of the US politicians promising to turn back the tide of migration.

But they will come anyway. Not necessarily because they're hungry, but because these days to move is to live. By undertaking their yearly journey, they are a part of the world, not apart from it. They will come and tell us that there is no turning back: we're all mestizos now.