When President Bush last week pronounced marriage "the most fundamental institution of civilization," he was in good company--at least rhetorically. That link has been proclaimed every time marriage has gone through changes, as it has frequently done throughout history.

The Roman statesman Cicero held that "the primary bond of society is marriage," suggesting an immutable institution. In fact, it has always been shaped by social currents, sometimes progressive, but often not.

Through the ages, the institution of marriage has been unfair to women, has banned the union of people of different races or religions, and has typically been far more concerned with property rights than romantic love--a very modern notion.

Now, as gay marriage has ballooned into a major issue of the presidential campaign, historians and voters alike are reflecting on an institution that truly is a foundation stone of society--for better and for worse.

"Since the 19th Century, people have treated family and marriage as the litmus test of society," said Michael Grossberg, an Indiana University professor who submitted a friend-of-the-court brief on behalf of several historians to the Massachusetts Supreme Judicial Court, whose ruling in favor of gay marriage triggered the national debate.

"Those who fear social change see any change in marriage and the family as a disaster," Grossberg said.

Ironically, the most enduring aspects of marriage tend to be the very opposite of those qualities its most vocal defenders associate with it. Romance, companionship, the warmth of family life, were rarely connected with marriage until recent times. In the beginning, it was chiefly an economic institution.

An engagement party in ancient Greece was a commercial transaction, said Marilyn Yalom in "A History of the Wife." "It was essentially an oral contract, made between the man who gave the woman in marriage--usually her father--and the bridegroom," Yalom wrote. "The bride was not present."

In this country, the conception of marriage as a transaction between father-in-law and son-in-law meant a woman went from being economically dependent on her father to the same status vis-a-vis her husband. Under a legal theory called "coverture," the married pair became one--the husband.

American wives couldn't own property--even that which they inherited from their parents--until various states gave them the right between 1839 and 1887. Before then, even the wages a working wife earned belonged not to her but her husband.

Husbands could physically discipline their wives, as long as they used what was euphemistically called "moderate correction." If that, or anything else, prompted women to leave home, their husbands would advertise the fact in newspapers, right alongside the ads Southern plantation owners placed for the return of runaway slaves.

'A state of slavery'

The U.S. Supreme Court was loath to tamper with that tradition of the man as lord and master of the household as late as 1911, when it rejected the idea that a wife could sue an abusive husband. The justices called the very thought "revolutionary," "radical and far reaching."

Little wonder then, that the 19th Century abolitionist and feminist leader Lucy Stone said, "Marriage is to woman a state of slavery."

And although clerics and statesmen praised marriage's civilizing virtues, the institution wasn't always available to all Americans.

Black Americans couldn't be legally married in the antebellum South. The idea was seen as threatening to slavery, upon which the region's economy depended. Even long after the Civil War, blacks and whites couldn't marry each other in many states. In the Western states, where anti-immigrant fever was high, Asians and whites were barred from marrying each other.

In 1967, when the U.S. Supreme Court finally voided those "anti-miscegenation" statutes, as they were called, 16 states still had them on their books. Even then, South Carolina didn't remove its statute until 1999.

America's marriage laws and traditions had a long prehistory by the time they came to this country, observed Harvard historian Nancy Cott, author of "Public Vows," a study of marriage and public policy in American history. Ultimately, they trace to Christian roots.

When the Roman Empire became Christian in the 4th Century, the church took charge of marriage. Chief among the rules it set for the institution was that marriage had to be for life--though earlier cultures had provisions for divorce--and monogamous.