Last week, a Texas jury convicted Warren Jeffs, leader of the polygamist FLDS Church, of two counts of child sexual assault against one of his 12-year-old plural wives. For Americans who are increasingly interested in the religion of the two Mormons running for president, Jeffs' conviction raises what could appear to be difficult questions about modern Mormonism.

There is no formal connection between Jeffs' FLDS Church and The Church of Jesus Christ of Latter-day Saints, as the Mormon Church is formally known. From 1852 until 1890, however, the Mormon Church did publically teach and practice polygamy as a way of imitating biblical prophets.

Given that history, many Americans ask themselves whether Jeffs' cocktail of religious authority, polygamy and child sex represents some dangerous essence concealed within the apparently wholesome veneer of mainstream Mormonism. Latter-day Saints themselves, however, are untroubled by this question. They know the chasm between themselves and Jeffs.

Ironically, however, it is precisely this chasm that causes Mormon anxiety. Many modern Latter-day Saints fear that in Jeffs they see a living relic of their own religious past, a piece of perfectly preserved 19th-century Mormonism, like a frightening prehistoric monster encased in amber. They do not like what they see, but given the enormous importance of historical memory for Mormon identity this fact presents a problem.

Answering any of these questions requires a nuanced understanding of history. If the stories they tell about their own origins are true, the spiritual progenitors of the FLDS began their split with mainstream Mormonism in the 1880s at the height of the federal government's intense legal crusade against plural marriage.

Modern Mormons and modern polygamists have thus been pursuing divergent paths for more than a century, a much longer period than the founding generation of Mormonism that they jointly claim. The FLDS are entitled to at least the dignity of their own historical development. A lot happens in a hundred years. It is naive to suppose that Jeffs' world is simply a projection of 19th-century Mormonism into the present.

That said, 19th-century Mormonism did contain some of the elements of Jeffs' story: plural marriage, prophets with loyal followers and geographic isolation. These elements, along with utopia building and a fiery millennialism, pushed 19th-century Mormonism in upon itself, creating barriers with the outside, "gentile" world and at times earning that world's suspicion and hostility.

At the same time, however, 19th-century Mormons embraced the broader world. Brigham Young, the living embodiment of early Mormonism, eagerly supported the transcontinental railroad, which he knew would shatter that isolation. He founded colleges and was a patron of the performing arts. Most dramatically, Mormons sent out thousands of missionaries to every corner of the globe that they could reach, and as the converts flowed in they brought their divergent cultures and perspectives with them. Nineteenth-century Mormons thus lived in the tension between isolation and openness.

By 1890, a decade of intense legal pressure had taken its toll. Thousands of Mormon polygamists were in jail. The Utah economy had all but ceased to function. The majority of Mormons had been deprived of their right to vote and the federal government was in the process of methodically dismantling the Mormon Church, confiscating its property and threatening to stop virtually all of its operations.

In extremis, some polygamists believed that the only alternative was to cling even more tightly to polygamy, retreat to more isolated locations, and abandon all connections with the outside world. If necessary these Mormons were willing to embrace apocalyptic destruction at the hands of the federal government. They became the progenitors of Warren Jeffs.

This, however, is not the path that Mormonism took. Then-Mormon church president Wilford Woodruff prayed and found a God willing to accept a church that survived and remained engaged in the world. Rather than retreating into dusty, ever more remote, polygamist utopias, the Mormon Church maintained its strained connection and openness to the outside world. To be sure, Woodruff transformed his religion, but he also preserved that portion of 19th-century Mormonism that modern polygamists reject.

Consider the efforts of the now iconic Mormon missionaries of today. Mormon missionaries want to convert you, but they also want to learn your language and be your friend. They are convinced that they bear a message that is deeply relevant to the realities of everyday life, rather than the esoteric ideology of a remote desert compound. In this they are the bearers of a Mormonism that goes back to the religion's founding.

Jeffs and his FLDS disciples, in contrast, have no missionaries. Their religion long ago abandoned the tradition of Mormon openness. They gave up engagement with the world for the isolation of the desert. For that reason, Jeffs tells us far less about both modern and historical Mormonism than many observers assume.

Nathan B. Oman is an associate professor of law at The College of William & Mary in Virginia.