What’s the most important thing for a historical novel to be? If you said “historically accurate,” bzzzt, sorry, let’s try again.

In recent years historians have shown that Thomas Jefferson fathered children with one of his slaves, Sally Hemings. That’s just about all we know, though. So what’s striking about Stephen O’Connor’s first novel, “Thomas Jefferson Dreams of Sally Hemings,” isn’t just that he persuasively invents a relationship almost entirely of whole cloth. It’s also a superb argument for why we do this imagining — in the novel’s wilder moments where O’Connor weaves Jefferson into the present day, he underscores how hard it is to untangle slavery from the American conversation.

The main story opens shortly after the American Revolution, when Hemings was still a child and Jefferson’s wife, Martha, had died. As Hemings becomes a caretaker for Jefferson’s children, she accompanies him to Paris when he becomes the U.S. minister to France.

As a teenager, she’s at once attracted and repulsed by him, “a paradox of tenderness and power.” When he first forces himself upon her, she’s firmly in the repulsion camp.

But a love story blooms across decades, one in which Jefferson is consumed by abject passion and respect for Sally’s intelligence — but not so much that he dare express it in public. And Sally is seduced by her master’s wisdom, and the secret moments when he doesn’t behave like her master. Their pillow talk is one part eroticism, two parts discussion of the political impediments to slavery-free America.

“This will be our own little country,” Sally tells him in bed, a line that elegantly captures the way their romance has a touch of government affairs about it.

But the country she hopes for (and that Jefferson only kind of hopes for) won’t exist in their lifetimes. And, O’Connor suggests, it eludes us still.

In brief vignettes, he transports Jefferson into a variety of modern settings — a prisoner being attacked by an abusive jailer for his hypocrisy on slavery, an art student pining for Sally in a subway car, an ape in a cage.

The wildness of the settings hint at how much history is an act of imagining, but they are also stark, inventive studies in power dynamics. Making Jefferson an ape means making him a beast, and exposes his beastliness as a slaveholder: “As long as no one thinks Thomas Jefferson is wrong, the harmony is total,” O’Connor writes.

“Thomas Jefferson Dreams of Sally Hemings” is a lengthy novel, but it hardly ever reads as one. Its chapters are clear, short and episodic, and O’Connor writes about slavery and intimacy with equal grace. His vision of romance in a society defined by division is wrenching, and proof that dreaming can expose reality better than any hard truth.

 Mark Athitakis is a book reviewer in Phoenix.

Thomas Jefferson Dreams of Sally Hemings
By: Stephen O'Connor.
Publisher: Viking, 610 pages, $28.