Italians are superstitious. Portuguese are lazy. Turks are dishonest. And the French? They're fat, and filthy besides.

Welcome to the world of Mark Twain, who died 100 years ago this week. We know Twain best from his novels about life in America, especially The Adventures of Tom Sawyer and The Adventures of Huckleberry Finn. In his time, however, he was more famous for documenting his adventures, overseas. He made his name as a travel writer, not as a novelist.

Twain's jabs at Italians and other groups come from his first travel book, Innocents Abroad (1869), his best-selling work during his lifetime. Then came A Tramp Abroad (1880) and, much later, Following The Equator (1897). Name a place where Americans went in the late 19th century, and Twain probably went there. He likely wrote about it, too.

But Twain's travelogues changed over time, with important lessons for our own day. From the scornful, often bigoted cynic of Innocents Abroad, Twain evolved into a passionate defender of diversity. Foreigners were not automatically worse than Americans, he decided; indeed, sometimes they were better.

Yet they remained different to him. Despite his later sensitivity toward other peoples, Twain never doubted that they were - and should be - distinct. That idea continues to pervade our world, discouraging us from mixing and melding in the ways that matter most.

Twain's first overseas expedition began in 1867 in New York, where he boarded a steamer headed for Europe and the Middle East. When Innocents Abroad came out two years later, Twain's satires of naive American tourists made readers snicker. But he reserved his sharpest invective for his foreign hosts, particularly if they were Catholic.

"We were in the heart and home of priestcraft - of a happy, cheerful, contented ignorance, superstition, degradation, poverty, indolence, and everlasting unaspiring worthlessness," Twain wrote from rural Italy. "And we said fervently, it suits these people precisely; let them enjoy it, along with the other animals."

And so it went, into Syria and Lebanon and Palestine. Though impressed by some of the buildings and landscapes, Twain was alternately bemused and revolted by the people inhabiting them. Middle Easterners, especially Muslims, were "thieves," "rascals," and most of all "savages."

More than a quarter-century later, Following the Equator reveals a very different Twain. From Australia and New Zealand to South Africa and India, he was struck first and foremost by the ways white colonists oppressed and dehumanized their subjects. In South Africa, Boers shot blacks with impunity; Australians did the same to aborigines.

"In many countries we have taken the savage's land from him, and made him our slave, and lashed him every day, and broken his pride, and made death his only friend, and overworked him till he dropped in his tracks," Twain wrote. "There are many humorous things in the world: among them the white man's notion that he is less savage than the other savages."

When the United States acquired the Philippines in 1898, Twain would become one of the most vociferous critics of American empire. "I am an anti-imperialist," he announced. "I am opposed to having the eagle put its talons on any other land."

At the same time, Twain worried that "other lands" were imitating America. In Ceylon (now Sri Lanka), he was appalled to encounter a group of students dressed just like the visitors in his delegation. "I was ashamed to be seen on the street with them," Twain wrote of his American companions. "Then I looked at my own clothes, and was ashamed to be seen on the street with myself."

Even as he developed a new appreciation for different countries and cultures, Twain demanded that they stay different. A similar assumption permeates many present-day critiques of "globalization," which is allegedly drowning other traditions in a pallid Western gruel. Thanks to film, TV, and the Internet, people are becoming more like us. And we don't like it any more than Twain did.

But why not? In defending "traditional" cultures from the Western behemoth, we make ourselves the arbiters of tradition itself. And we dismiss the dreams and desires of non-Western peoples who might have their own good reasons to change.

On the centennial of Mark Twain's death, let's renew his commitment to human freedom and difference. But let's also insist that all remain free to alter their differences as they see fit. Only then will we realize the common humanity that should bind us all.

Jonathan Zimmerman teaches history at New York University and is the author of "Innocents Abroad: American Teachers in the American Century."