Edith B. Gelles is a senior scholar at Stanford’s Michelle R. Clayman Institute for Gender Research and author of “Abigail and John: Portrait of a Marriage.”

It doesn’t give away too much to mention that this book begins and ends with the unlikely same-day deaths of its two protagonists on the 50th anniversary of the Declaration of Independence, the founding document for which they, more than any others, were responsible. Nor does it spoil the story to reveal the book’s theme: that one of them, John Adams, informs Americans who we actually are as citizens, while the other, Thomas Jefferson, explains how we would like to see ourselves. This magisterial double biography recounts not only the lives of these two greatest founders but also the creation of the republic. It describes the world’s first successful democratic revolution and the founding of the first non-monarchical republic. It has nothing of military strategies or engagements or war heroes; it is a book about ideas as represented by two philosophical statesmen, and it makes political history and philosophy exciting.

Gordon S. Wood, emeritus professor of history at Brown University and undisputed dean of 18th-century-America historians, returns in “Friends Divided” to topics that have burnished his career with many honors, among them the Bancroft and Pulitzer prizes. Wood offers a fresh account and discerning insights about the contingency of our founding era and how two seemingly ordinary men emerged to represent its conflicts and resolution. In Wood’s hands, Adams and Jefferson become Shakespearean in stature. The telling of their biographies is roughly chronological but also topical. An early chapter titled “Independence” assesses the notion that “all men are created equal” through an 18th-century lens, holding up to the light Adams, the New Englander whose family “never owned a slave,” as he claimed, and Jefferson, the wealthy slave-holding Virginian who occasionally argued for the liberation of slaves. Both men grappled with the significance of “equal” when it came to issues of race and class (but never gender); the categories were viewed differently in that era, before the Civil War ended bondage and the later upheavals of industrialization and capitalism redefined class.

Wood scrutinizes the missions abroad of the men as ministers to France, England and the Netherlands, where all the Adamses and Jefferson became warm friends. Then, moving on to a chapter called “Constitutions,” the author provides a magnificent account of the thinking that went into the creation of individual state constitutions after independence was declared; he reveals how the states’ experiences aided the creation of a national government built on three branches.

“Friends Divided,” by Gordon S. Wood (Penguin Press)

Adams was ever conscious of his lower-class origins, born of a father who was a farmer and shoemaker, though his mother descended from the higher-class Boylstons of Massachusetts. Deciding early to eschew the clergy, he first taught school before settling on a law career, rising eventually, in his own estimation, to become the most successful lawyer in Boston. Jefferson, who always knew that he was a gentleman, grew up surrounded by slaves, inherited several plantations and married a rich widow, Martha Wayles Skelton, daughter of another plantation owner. Like Adams, he eventually studied law, but unlike Adams, he was never dependent upon its practice for his livelihood. Both men had capacious minds, read widely and deeply, and collected libraries of classical and modern thinkers. (Both peppered their correspondence with quotations in Greek and Latin.)

Jefferson, according to Wood, had the more inquiring and versatile mind; the Virginian was interested in history, philosophy, science and medicine, and had an imagination that was probing and experimental. Adams was more penetrating and sensitive, with a deep appreciation for nuance and for understanding human character and motivation. Moreover, and perhaps because of their divergent upbringings, they differed in personality and persona. Adams was famously contrarian, outspoken and passionate, whereas Jefferson was famously silent, polite, impenetrable and opaque. Despite their differences, for some years the two men shared a commitment to the radical agenda of separation from the British Empire and the creation of a new nation.

The French Revolution caused a rift between Adams and Jefferson. Wood explores how that European upheaval resonated in the barely formed new American constitutional government. Jefferson — who had lived in France, loved its culture and style, and never wavered from his optimistic belief that the revolution and subsequent bloodletting would lead to a better world (“a little rebellion now and then is a good thing”) — couldn’t have been more different from Adams. Over the years, possibly from the time of his earliest experiences in the Continental Congress and then as a diplomat, Adams became more suspicious of human nature, reverting, perhaps, to his Puritan origins in his belief that rulers would become dishonest and corrupt. “You,” he told Jefferson, “are afraid of the one — I of the few. . . . You are apprehensive of Monarchy, I, of Aristocracy.” The election of 1800, after “the most vicious and scurrility-ridden” political campaign in American history, confirmed their estrangement. Adams retired to Quincy, Mass., and Jefferson, after his presidency, to Monticello, and for 12 years they did not communicate. Then, following a reconciliation in 1812, the two elderly statesmen resumed an amazing correspondence.

Over the past two centuries, Woods concludes, “Jefferson’s star has remained ascendant while Adams’s seems to have virtually disappeared from the firmament.” There is no monument to Adams in the nation’s capital. As the two founders agreed in their final correspondence, no one but they could ever write an accurate history of their times. Wood comes close.

But like so many historians of the period, he seems to give Jefferson a pass on his slave ownership. Jefferson’s contributions to the nation’s founding and beautiful, eternal language he crafted as America was born seem to absolve him from lasting responsibility. Wood rightfully cites the sentiments Jefferson embraced in his “Notes on the State of Virginia” and other writings — that black people were inferior in terms of physical attributes and mental reasoning; that female slaves were most valuable as breeders — but it seems appropriate that a hero’s life be measured against his conduct overall.

In the end, history must judge between words such as “Jeffersonian democracy” and behavior that led two generations later to more than a half-million deaths on the battlefield and to Jim Crow and its current incarnations — not an insignificant portion of the American story. And monuments should honor the prophet who told the truth about who we are as well as the optimist who advanced a more sanguine picture of our system of beliefs.

Friends Divided
John Adams and Thomas Jefferson

By Gordon S. Wood

Penguin Press. 502 pp. $35