General Douglas MacArthur, in being relieved of his command by President Harry Truman in the Korean War, famously declared that "old soldiers never die, they just fade away." The last part of that has most often applied as well to defeated presidential nominees.
F. Scott Fitzgerald somewhat similarly noted in "The Last Tycoon" that "there are no second acts in American lives" -- an observation that also could be said in politics of most also-rans in presidential sweepstakes.
But the recent surge of diplomatic energy and success of John Kerry, who lost his bid for the presidency in 2004 to George W. Bush, suggests that the former Massachusetts senator is enjoying an impressive second act as President Obama's second-term secretary of state.
Mr. Kerry's persistent and diligent pursuit of a deal with Iranian negotiators to slow the Tehran regime's nuclear weapons program is still far from achieving the ultimate goal. But the agreement for a six-month pause in exchange for a limited diminution of UN-backed economic sanctions is a hopeful and somewhat surprising first step.
Amid fierce condemnation from Israeli Prime Minister Benjamin Netanyahu, Mr. Kerry has used personal diplomacy in a conspicuously bolder and tougher way than his predecessor, Hillary Clinton, ever pursued. He has set the Obama administration on a riskier but potentially more beneficial course in the troubled Middle East.
Mr. Kerry has done so even as he has sought to shatter the stalemate on an Israeli-Palestinian peace agreement that persisted throughout the first term of Mr. Obama. In the process, Mr. Kerry has pivoted smoothly from his long legislative career and chairmanship of the Senate Foreign Relations Committee to a dogged on-the-ground, hands-on shuttle diplomacy.
Unintentionally, no doubt, he has helped provide much-needed political cover for a president enduring a battering at home, resulting from the inept rollout of the health-care insurance plan intended to be the crown jewel in his presidency.
At the same time, Mr. Obama's own gamble of going to Congress before taking military action against Syria, and now Kerry's Iran deal, have made foreign policy a ray of hope in the administration's autumn of discontent.
Mr. Kerry, on his past record, would seem to be an unlikely public figure to shine on the international stage. Although he made it known he wanted the job of secretary of state, it came to him second-hand only after Mr. Obama's nomination of Susan Rice, now his national security adviser, self-destructed in the handling of the Benghazi consulate terrorist attack.
But Mr. Kerry's whole rise to political prominence was marked by unforeseen turns, from his return from the Vietnam war as an outspoken critic testifying before Congress to his election first to the House and then to the Senate. In 1984, he seemed on the verge of defeat in his Senate bid when his Democratic primary foe unwisely attacked his military record and it backfired.
His 1994 presidential bid benefited from the implosion of Democratic frontrunner, Howard Dean, in the Iowa caucuses but was undone by a Republican smear campaign against his decorated Navy combat service in Vietnam. His opponents did an effective job of casting him a wealthy Boston windsurfing aristocrat unable or unwilling to hit back against the smears and ridicule. He returned in defeat to the Senate in what appeared to be end of his aspirations for national elective office.
In leaving Congress, Mr. Kerry has found new stature, new energy and intensity in his diplomatic second act. Yet his old congressional connections could hold a key to completing the Iranian deal. Critics on Capitol Hill are poised to push for greater sanctions against the regime even as he lobbies for limited easing of them.
Altering Ronald Reagan's formula of "trust but verify" to put the emphasis on the latter, Mr. Kerry has to convince these critics that he will insist on solid evidence of Iranian compliance in dismantling its bomb-making capacity.
Accordingly, his diplomatic shuttling between allies and a hostile regime that could not be cracked by Hillary Clinton now brings him back to his old Senate stamping ground, where he will need to overcome the next barrier to his diplomatic breakthrough in Iran.
Jules Witcover is a syndicated columnist and former long-time writer for The Baltimore Sun. His latest book is "Joe Biden: A Life of Trial and Redemption" (William Morrow). His email is firstname.lastname@example.org.