The Hemingses of Monticello: An American Family, by Annette Gordon-Reed, New York: W.W. Norton & Company, 800 pages, $35

In 1775 the English essayist and lexicographer Samuel Johnson wrote a spirited political pamphlet titled Taxation No Tyranny. His subject was the loud and increasingly aggressive rhetoric coming from the American colonies, where criticism of British economic policy was giving way to calls for popular revolution. "How is it," Johnson retorted, "that we hear the loudest yelps for liberty among the drivers of Negroes?"

It's still a good question. Perhaps no one illustrates the paradox better than Thomas Jefferson. The celebrated author of the Declaration of Independence, which famously declares that "all men are created equal" and are born with the inalienable rights to "life, liberty, and the pursuit of happiness," Jefferson was also a slaveholder, a man whose livelihood was rooted in the subjugation of hundreds of human beings, including members of his wife's family and his own.

At the center of Jefferson's tangled, frequently horrifying web of blood and bondage were two women: Elizabeth Hemings and her daughter Sarah, better known as Sally. Elizabeth, the daughter of an African slave and an English sea captain, was the slave mistress of a Virginia slave owner and broker named John Wayles. Sally Hemings was the youngest of their six children. Wayles also had children from his three marriages, including a daughter named Martha. Sally Hemings, in other words, was Martha Wayles' half-sister. At her father's death in 1773, Martha inherited his human property, including Elizabeth and Sally Hemings. In 1772 Martha married Thomas Jefferson. Thus the Hemingses came to Monticello.

In 1782 Martha died from complications after giving birth to her sixth child with Jefferson. Among those with him at her deathbed were Elizabeth and Sally Hemings, who then was 9 years old. Edmund Bacon, one of Jefferson's overseers at Monticello, reported that as Martha lay dying she asked her husband not to remarry. "Holding her hand, Mr. Jefferson promised her solemnly that he would never marry again," Bacon recalled. "And he never did."

That doesn't mean Jefferson became celibate. In 1789, while serving as U.S. envoy in Paris, he almost certainly began a four-decade-long relationship with his late wife's half-sister. (In addition to the oral testimony of numerous Hemings family members, the evidence for their relationship includes DNA tests conducted in 1998 establishing that a Jefferson family male fathered Sally Hemings' son Eston.) At this point Sally Hemings was 16.

It was an affair the historian Edmund S. Morgan has called a "monogamous spousal relationship." In her extraordinary new book The Hemingses of Monticello, Annette Gordon-Reed, a professor of history at Rutgers University and a professor of law at New York Law School, uses a more specific term: concubine, which Virginia law defined at the time as a woman living with a man who was not her husband. If Sally Hemings were white, we might describe her relationship with Jefferson as a common-law marriage. But as Gordon-Reed reminds us, "Any black woman who lived with a white man could only have been his concubine. It was legally impossible to be anything else."

This relationship apparently lasted until Jefferson's death in 1826, by which time Hemings had given birth to seven of his children, four of whom survived into adulthood. In his will, Jefferson formally emancipated two of them, James Madison Hemings and Thomas Eston Hemings. The other two, William Beverly Hemings and Harriet Hemings, simply left Monticello on their own in the early 1820s to live—"pass"—as white. (All three males, it's worth noting, were named after men Jefferson knew or admired, a common practice among Virginia's planter elites.) Eight years after Jefferson's death, his daughter Martha Randolph quietly freed Sally Hemings, who was then 53 years old. Why didn't Jefferson emancipate her too? "Formally freeing Hemings," Gordon-Reed observes, "while also emancipating two people obviously young enough to be their children, would have told the story of his life over the past thirty-eight years quite well."

Among the many achievements of Gordon-Reed's compelling, if slightly repetitive, book is her vivid illumination of these previously hidden lives. She persuasively argues that Hemings exacted a promise from Jefferson that proved no less momentous than the one he had granted his dying wife. In essence, 16-year-old Hemings, who was pregnant with Jefferson's child and working as his domestic "servant" in Paris, chose to return to America with him, rather than remain in France, where she could have formally received her freedom. (By law any slave that set foot on French soil was automatically free.) She did so because Jefferson promised to emancipate her children when they became adults—a promise he kept. In exchange, she lived as his concubine. "Like other enslaved people when the all too rare chance presented itself," Gordon-Reed writes, "Hemings seized her moment and used the knowledge of her rights to make a decision based upon what she thought was best for her as a woman, family member, and a potential mother in her specific circumstances."

Jefferson apparently cared for Sally Hemings and their children, and he clearly treated members of her family (some of who were also his deceased wife's family) with much consideration. Elizabeth Hemings, for instance, became something of a revered matriarch. Her sons Robert and James (brothers to Sally Hemings and Martha Jefferson) received instruction in the skilled trades of barbering and cooking, respectively.

Both were permitted to work for private wages, and both enjoyed relative freedom of movement outside of Monticello—so long as they came running at their master's command, of course. "Despite their status on the law books," Gordon-Reed writes, "Jefferson treated them, to a degree, as if they were lower-class white males." Eventually, Jefferson freed them both.

But let's not draw too rosy a picture. As part of the marriage settlement for his sister Anna, Jefferson handed over the slave Nancy Hemings (another of Elizabeth Hemings' offspring, though not by John Wayles) and her two children. When Anna's husband decided to sell these three slaves, Nancy Hemings implored Jefferson to buy them back so they could remain together as a family. Jefferson bought Nancy, an expert weaver, and her young daughter, but refused to buy her son. The family was split apart. "No matter how 'close' the Hemingses were to Jefferson, no matter that he viewed some of them in a different light and did not subject them to certain hardships," Gordon-Reed writes, "their family remained a commodity that could be sold or exchanged at his will."

Which brings us back to Samuel Johnson and his quip about slaveholders yelping for liberty. Does the fact that Thomas Jefferson owned slaves—probably including his own children—negate the wonderful things he wrote about inalienable rights in the Declaration of Independence? To put it another way, why should anyone listen to what Master Jefferson (or other slaveholding Founders) had to say about liberty and equality?

It's important to remember that the idea of inalienable rights didn't start or stop in the year 1776. The historian Gordon S. Wood, in his superb 1991 book The Radicalism of the American Revolution, argues that "to focus, as we are apt to do, on what the Revolution did not accomplish—highlighting and lamenting its failure to abolish slavery and change fundamentally the lot of women—is to miss the great significance of what it did accomplish." In Wood's view, by destroying monarchical rule and replacing it with republicanism, the American revolutionaries "made possible the anti-slavery and women's rights movements of the nineteenth century and in fact all our current egalitarian thinking." They upended "their societies as well as their governments…only they did not know—they could scarcely have imagined—how much of their society they would change."

As evidence, consider two very different figures whose lives intersected with slavery in the 19th century: the abolitionist Frederick Douglass and the pro-slavery politician John C. Calhoun. An escaped slave and self-taught author and orator, Douglass understood better than most just how potent the Declaration's promise of inalienable rights could be. "Would you have me argue that man is entitled to liberty? That he is the rightful owner of his own body?" Douglass would demand of his mostly white audiences. "There is not a man beneath the canopy of heaven that does not know that slavery is wrong for him."

Calhoun, by contrast, believed the Declaration's assertion that "all men are created equal" was "the most dangerous of all political error." As he put it in an 1848 speech, "For a long time it lay dormant; but in the process of time it began to germinate, and produce its poisonous fruits." This false notion of equality, Calhoun continued, "had strong hold on the mind of Mr. Jefferson…which caused him to take an utterly false view of the subordinate relation of the black to the white race in the South; and to hold, in consequence, that the former, though utterly unqualified to possess liberty, were as fully entitled to both liberty and equality as the latter."

Think about what Calhoun is saying here. The idea that "all men are created equal" has slowly developed in the American consciousness, producing the "poisonous fruits" of the anti-slavery movement. Jefferson may or may not have intended such an outcome; he certainly did little actively to bring it about, though he did denounce slavery and its brutalizing impact on white society. But the libertarian ideas that inspired Jefferson, the ones coursing through the Declaration of Independence and later through the Constitution, nonetheless did bring it about. Douglass welcomed that result; Calhoun despised it.

That's why Jefferson's words matter. In spite of his despicable actions, he gave eloquent and resounding voice to the ideas that have been at the forefront of human liberty for hundreds of years. That members of the Hemings family may have heard such rhetoric while they lived in bondage further highlights the tragedy of their terrible situation. Thanks to Annette Gordon-Reed, these forgotten and silent individuals at least have the opportunity to register their own verdicts on this shameful period.

Damon W. Root is an associate editor of reason.