John Adams and Thomas Jefferson will always be linked, as Founding Fathers and presidents. They even died on the same day — July 4, 1826. At the  Continental Congress and on diplomatic missions to Europe, they became close friends. Later, their friendship would sour, and they turned into political enemies, before making amends later in life.

Historians Joanne Freeman, professor and director of graduate studies in history at Yale University; Carol Berkin, professor of history at Baruch College and the Graduate Center; and Douglas Ambrose, Sidney Wertimer Jr. associate professor of history at Hamilton College, talk about Adams and Jefferson.

What's the best thing about early American history?
Carol Berkin: I have always thought that the birth of a nation was the most exciting moment in its history, but I was disturbed by the tendency of Americans to think of the founding generation of men as "demigods" without any flaws and without idiosyncrasies. In my research, I discovered Adams and Jefferson had fascinating, complex, and flawed characters and this made their accomplishments so much more remarkable.

Douglas Ambrose: Quite simply this era contains some of the most intriguing and significant figures in all of American history. What really made Adams and Jefferson stand out from the other fascinating individuals of the era was their mutual correspondence between 1812 and 1826. For my money, their letters to one another are among the best things either ever wrote -- witty, often profound, and always revealing. Love or loathe either Adams or Jefferson (or both), these letters display their wonderfully self-conscious and always interesting reflections about the era and their roles in it.

Why is John Adams interesting?
Carol Berkin: Adams was so wonderfully neurotic — sometimes so unsure of himself, sometimes so pompous, always anxious that people recognize his talents. He seemed often to doubt himself, yet he was, after all, a brilliant lawyer, a fine political theorist, and he devoted himself unflinchingly to the cause of American independence. He reminds me of the anti-heroes of modern fiction and film: neither handsome nor dashing, full of self-doubt, yet capable of great deeds.

Adams was always transparent, but Jefferson, on the other hand, was secretive. It is this closed off quality to Jefferson that fascinates me.

Joanne Freeman: Many things about Adams fascinate me, but I've always been particularly fond of his sense of humor and his self-deprecating awareness of some of his flaws, even as he flailed away while fully caught up in them. Adams has always struck me as a particularly "human" founder, as preserved on paper.

Were Adams and Jefferson friends or enemies?
Carol Berkin: Longevity and the history they shared defined their relationship. In their old age, they came to see one another as the living reminder of the revoclution. The relationship was sometimes tumultuous, but they were, in the end, comrades in arms.

Douglas Ambrose: When Jefferson arrived in Paris in 1784 to join Benjamin Franklin and Adams as ministers to France, Adams much admired and liked Jefferson. Adams famously remarked that the news that Congress had appointed Jefferson "gives me great pleasure." Although Jefferson was less effusive, once he and Adams started working together he deepened his respect and affection for him.

The low point of their relationship had to be the years immediately following the nasty election of 1800. Abigail's famous exchange of letters with Jefferson in 1804 demonstrates just how bitter the feud had become.

I think the high point of the relationship is Jefferson's letter of condolence to Adams upon hearing of Abigail's death. Nothing Jefferson ever wrote is as moving as these heartfelt words to his old suffering friend:

"Tried myself, in the school of affliction, by the loss of every form of connection which can rive the human heart, I know well, and feel what you have lost, what you have suffered, are suffering, and have yet to endure. The same trials have taught me that, for ills so immeasurable, time and silence are the only medecines. I will not, therefore, by useless condolances, open afresh the sluices of your grief nor, altho' mingling sincerely my tears with yours, will I say a word more, where words are vain, but that it is of some comfort to us both that the term is not very distant at which we are to deposit, in the same cerement, our sorrows and suffering bodies, and to ascend in essence to an ecstatic meeting with the friends we have loved and lost and whom we shall still love and never lose again. God bless you and support you under your heavy affliction."

After the election of 1800, few would have imagined that Adams and Jefferson would one day not only correspond with each other, but that the correspondence would reveal such deep mutual affection and respect.

How did Abigail Adams feel about Jefferson?
Carol Berkin: Abigail was a good "hater"; when she believed someone had been unfair or damaging to her husband, her fierce loyalty to John prompted a determined anger and hatred in her. When the break came with Jefferson over national politics, I think Abigail fueled the fire of John's anger.

Douglas Ambrose: Although Adams and Jefferson developed their relationship in Philadelphia in 1775-1776, when Abigail was back in Braintree, she played a rather large role in the 1780s, when the Adamses were in Paris and then London and Jefferson was in Paris. She impressed Jefferson with both her intellect and her heart, caring at times for the widowed Jefferson's daughters. After she and John had moved to London, she characteristically wrote to Jefferson "that nothing would give more pleasure to your friends here than a visit from you, and in that number I claim the honor of subscribing myself."

Yet she fully supported John during the years when he and Jefferson did not correspond. Her famous exchange with Jefferson in 1804 powerfully demonstrates both her loyalty to her husband and the pain she experienced from what she considered Jefferson's dissembling. When Adams and Jefferson resumed their correspondence, she too wrote once more -- with warmth -- to Jefferson, renewing "the Friendly intercourse and harmony" that political "Back wounding calumny" had interrupted but could not end.

What did it mean to be a Federalist or a Republican in the 1790s?
Joanne Freeman: A quick-and-dirty summary: Federalists favored a strong national government, tended to distrust mass popular politicking outside of elections, and favored strong trade connections with Great Britain; "money-men" and merchants, New Englanders and city-dwellers tended to be attracted to the Federalist persuasion. Southerners, farmers, and eventually, ambitious members of the lower ranks tended to migrate toward Republicanism, which preferred a weaker national government, was friendlier to popular politicking, and favored the support of revolutionary France.

Douglas Ambrose: Federalists and Republicans differed on a number of points, including the meaning of "federalism," the dangers to republican government, and foreign policy.

In broad terms, Federalists favored an "energetic" central government and weaker state governments, while Republicans wanted a limited central government and strong state governments. Federalists, in pursuit of a strong central government, interpreted the Constitution broadly, arguing that it granted certain unspecified "implied" powers — such as the power to create a national bank — to the central government.

Republicans, on the other hand, interpreted the Constitution narrowly or strictly. For them the Constitution limited the central government to certain specific powers; to allow that government to assume more powers than those specified opened the way to tyranny. For Republicans the greatest threat to republican government was a powerful, distant central government controlled by a few self-serving "aristocrats."

Federalists, who also considered themselves defenders of republican government, feared the chaos and instability they associated with an excess of democracy. For Federalists, too much democracy threatened order and property, the essential bases of "true" republican society.

Finally, the French Revolution and its aftershocks profoundly affected the first party system. Federalists generally saw the French Revolution as evidence of their greatest fears of unchecked democracy while Republicans tended to support the Revolution as a progressive and necessary -- if at times painful — step toward a better world.

What did Adams and Jefferson think of each other as politicians?
Joanne Freeman: In early national America, high-ranking political leaders saw themselves as public men doing their civic duty, but not as "politicians." Judging Jefferson as a public man during Jefferson's presidency, Adams considered him a somewhat self-serving, ambitious "intriguer" — a man who had played the game of politics and earned himself the nation's highest office. (Of course, at this point, Adams was still wounded from the partisan conflicts of his own presidency, in which Jefferson played a leading role.) Jefferson probably considered Adams oddly self-destructive in public life, a man who was too honest for his own good and too admiring of the British political system. Of course, each man also saw the good in the other -- personally and politically -- particularly in old age, when they rebuilt their friendship.

Who was the more successful president?
Carol Berkin: Historians reevaluate the past constantly — and popular opinion changes, often in light of present circumstances. There might be many people who feel the Alien and Sedition Acts [under Adams] were regrettable, but necessary to protect the nation's security, while Jefferson's refusal to enter the world arena of war might be seen as a weakness. This is not necessarily my own view, but I make the argument only to suggest that evaluative judgments -- successful, failure -- are never objective.

Joanne Freeman: In some respects, both men had unsuccessful presidencies. Jefferson takes the blame for the highly unsuccessful Embargo Act of 1807 that accomplished little more than bringing economic hardship to New England. Along similar lines, Adams should get credit for making peace with France during his presidency rather than taking the nation into war; he later declared this act one of the great achievements of his political life. All in all, neither man enjoyed a stellar presidency.

Douglas Ambrose: One cannot help but label Adams' presidency "unsuccessful," although keeping the country out of a full-scale war with France was a positive achievement. But Jefferson's presidency was hardly an unqualified success. Certainly there were some notable achievements in his first term, with the Louisiana Purchase and the Lewis and Clark mission topping the list. Even these successes, however, raise questions about how one defines "success." Some argue that the Louisiana Purchase not only violated Jefferson's strict interpretation of the Constitution, but also opened the west to slavery, thereby contributing to sectional conflict in the decades ahead. And Jefferson's second term can only be termed a disaster; the Embargo Act devastated the economy, did nothing to advance American interests internationally, temporarily hurt his party, and probably made America weaker when war came in 1812.

How did their friendship survive?
Carol Berkin: Their generation had passed; they were, in a sense, the relics of an earlier era and they reached out to each other in their old age. Both men wanted to reminisce, to recapture the richness of the revolutionary experience and they turned to one another. Like many people who reach old age, they came to see that their differences were less important than their shared experiences.

Joanne Freeman: Although Adams and Jefferson became ardent political foes in the tumultuous 1790s, they managed to preserve some respect — each for the other -- as a man. By their retirement, the two men had known each other for well over 30 years; they had toiled together for American independence. When both men had permanently stepped out of public life, they gained some distance from their partisan differences, and their personal fondness for one another came back to the fore. Their correspondence during this period is a remarkable look back at the most formative years of the nation's founding from two personal points of view, told by two of the most active participants in the period's major political events. The humor and humanity in many of these letters is sometimes quite moving.

Douglas Ambrose: In part the affection that Adams and Jefferson had developed for one another in the 1770s and 1780s never totally vanished; one catches glimpses of fond memories even during the "dark" years after 1800. But time and some distance from the intense party battles of their respective administrations made the reconciliation possible. What made the reconciliation happen, however, were heroic and sustained efforts of Benjamin Rush, an old friend and fellow signer of the Declaration of Independence. If not for his intervention, Adams and Jefferson may never have revived their correspondence and friendship. Once initiated, the post-1812 correspondence continued in part because, following Adams's suggestion, both men tried to explain "ourselves to each other." Of course, both Adams and Jefferson also wanted to explain themselves and "their" Revolution to posterity. As much as their letters addressed each other, they also addressed what they knew would be a curious and attentive posterity. Each man wanted to craft his version of what the Revolution was and should mean to future generations. Their friendship certainly made the correspondence possible, and that friendship contributed to the respectful and even affectionate tone of much of the correspondence, but a need to shape the memory and meaning of the Revolution fueled both men's efforts to leave a record of their understanding of their individual and collective achievements.