Washington (CNN) Tragedy has not just afflicted Joe Biden, it has shaped his political soul.

In the latest personal devastation, the Vice President must now endure the torment of burying a second child, after his beloved son Beau died from brain cancer Saturday night.

It's particularly heartrending because Beau, 46, was also a victim of an earlier incident that shattered Biden's life, a car crash at Christmas in 1972 that killed his first wife and an infant daughter and badly injured another son as well as Beau.

Stricken with grief back then, Biden contemplated vacating the Delaware Senate seat he had just won as a young rising star of the Democratic Party, but his decision to endure became the foundation on which he built his political creed and public service. In a famous photo at the time, Biden was seen being sworn into the chamber in his sons' hospital room.

Biden's daily commute between Washington and Wilmington to be with young sons Beau and Hunter became the stuff of political legend and earned him the nickname 'Amtrak Joe.'

But in a deeper sense, his personal tribulations cemented in Biden an almost mystical reverence for family. It pulsates through his politics and is at the root of his love affair with the U.S. Senate, which sustained him when his home life was torn apart and where he served for nearly four decades.

Biden spoke eloquently about that earlier tragedy at a commencement address at Yale University just a couple of weeks ago. Beau's terminal condition was not publicly known then, but after his death Biden's words took on extra meaning.

"Looking back on it, the truth be told, the real reason I went home every night was that I needed my children more than they needed me," he said, noting that pundits suggested his absences from Washington would wreck his political career.

"But I realized I didn't miss a thing. Ambition is really important. You need it. And I certainly have never lacked in having ambition," Biden said. "But ambition without perspective can be a killer."

That personal tragedy, and his own later near-death experience after a cranial aneurysm in 1988, also molded Biden's garrulous political persona. Sentiment and emotion are always just under the surface with Biden. They often burst out in unpredictable ways during his public speeches, but his unrestrained style helps him charm audiences, to the benefit of his political career.

His mythologizing of his upbringing in a home full of love but little money gives Biden instant kudos with blue-collar voters -- something his boss President Barack Obama lacks.

Photos: Photos: Vice President Joe Biden Photos: Photos: Vice President Joe Biden U.S. Vice President Joe Biden began his career in politics in 1972, winning election to the Senate at the age of 29 (he was 30 when he took office). The Delaware Democrat was reelected to the Senate six times, including 2008, before becoming the 47th vice president of the United States. Hide Caption 1 of 14 Photos: Photos: Vice President Joe Biden Biden is sworn in for his second term as vice president by Supreme Court Justice Sonia Sotomayor, with his wife, Jill, and son, Beau, by his side, on January 21, 2013, in Washington. Hide Caption 2 of 14 Photos: Photos: Vice President Joe Biden Biden presides over a ceremony in Baghdad to formally mark the end of the U.S. combat mission in Iraq on September 1, 2010. Hide Caption 3 of 14 Photos: Photos: Vice President Joe Biden Biden and President-elect Barack Obama wave to the crowd at their election night party at Grant Park in Chicago on November 4, 2008. Hide Caption 4 of 14 Photos: Photos: Vice President Joe Biden Biden speaks after being introduced as Obama's running mate while campaigning together after the Democratic National Convention in 2008. Hide Caption 5 of 14 Photos: Photos: Vice President Joe Biden From left, former Sen. John Edwards, Biden, Obama and Sen. Hillary Clinton at a debate of Democratic presidential candidates on April 26, 2007, in Orangeburg, South Carolina. Hide Caption 6 of 14 Photos: Photos: Vice President Joe Biden Biden releases his memoir, "Promises to Keep: On Life and Politics," in 2007. Hide Caption 7 of 14 Photos: Photos: Vice President Joe Biden As a ranking member of the Senate Foreign Relations Committee, Biden is interviewed on NBC's "Meet the Press," concerning the war in Iraq on August 14, 2005. Hide Caption 8 of 14 Photos: Photos: Vice President Joe Biden While chairman of the Senate Foreign Relations Committee, Biden meets Afghan students during a visit to Kabul in 2002. Hide Caption 9 of 14 Photos: Photos: Vice President Joe Biden Biden is welcomed back after undergoing surgery for an aneurysm in 1988. Hide Caption 10 of 14 Photos: Photos: Vice President Joe Biden Biden announces his candidacy for the Democratic presidential nomination in 1988. After three months he drops out, following reports of plagiarism and false claims about his academic record. Hide Caption 11 of 14 Photos: Photos: Vice President Joe Biden While on the Senate Judiciary Committee, Biden meets with Sen. Frank Church, center, and Egyptian President Anwar Sadat after the signing of the Egyptian-Israeli Peace Treaty in 1979. Hide Caption 12 of 14 Photos: Photos: Vice President Joe Biden President Jimmy Carter and Biden attend a reception for the Delaware Democratic Party in 1978. Biden was the first senator to endorse Carter's presidential candidacy two years earlier. Hide Caption 13 of 14 Photos: Photos: Vice President Joe Biden At a convention in 1972, Biden and his first wife, Neilia, and his two sons take a photo with Delaware Gov.-elect Sherman W. Tribbitt and his wife Jeanne. Neilia Biden died in a car accident a few months later, after his first election to the Senate, along with their infant daughter, Naomi. Hide Caption 14 of 14

"My dad used to have an expression: 'Don't tell me what you value. Show me your budget, and I'll tell you what you value,'" Biden often recounted during the 2008 campaign.

The accident that killed his wife and daughter also forged a bond between Biden and pillars of the Democratic Party like firefighters and police unions.

At an International Association of Fire Fighters conference in 2007, Biden said the firemen extricated his sons from the car wreck; got him to hospital during a snow storm when he was critically ill with the aneurysm; and saved his home when it was struck by lightning with his second wife Jill inside.

"You took care of me in the worst times of my life, literally saved the lives of three Bidens, maybe four, and you did it like you always do, never expecting to be thanked," he said, in a typical blend of pathos and blarney which left few dry eyes.

Sometimes, the teetotaling Biden seems to storm through life like it's all one big Irish wake, consoling the bereaved, slapping backs, sowing gaffes, while the pomposity of a former senator is debunked with the smile of a man who knows self mockery.

Like many men who have looked death in the eye, Biden radiates a love for life and never seems uncomfortable in his own skin.

Ironically, his personal confrontations with the fragility of life have made him, along with Bill Clinton, the most sought after eulogist in Washington.

His almost slapstick swearing in of new senators is appointment viewing in Washington, as Biden chats up grannies and goofs around with kids, apparently enjoying himself far more than anybody else.

His flashing grin, aviator shades and blue collar moxie have spawned mock tributes on the satirical website "The Onion," where the "President of Vice President of Vice" is depicted as shirtless, washing his Trans Am in the driveway of the White House.

Biden has also faced more serious criticism and consequences for his gaffes. Even after Biden was chosen for the Democratic ticket in 2008, Obama aides fretted over the damage the vice presidential candidate's loose lips could do.

In 2012, he showed that he could still mangle talking points when he stepped all over Obama's plans to roll out his backing for gay marriage by committing the cardinal vice presidential sin on "Meet the Press" of getting ahead of the boss.

Yet White House insiders say Obama values Biden's loyalty and appreciates how he steadied the reelection campaign after the president's first disastrous debate with Republican nominee Mitt Romney. That appreciation has now turned to deep affection for a man who has played second fiddle to the president despite having an outsize political ego of his own.

"Joe is one of the strongest men we've ever known. He's as strong as they come, and nothing matters to him more than family. It's one of the things we love about him," Obama said in a statement on Beau Biden's passing.

It's unclear how much Beau Biden's declining health played into his father's reluctance, so far, to launch a long-odds White House campaign in 2016 -- having already lost a presidential campaign more than once.

The tragedy has also become one of those rare moments in Washington where political hostilities are suspended, with politicians from both sides of the aisle reaching out.

Biden's foe on the vice presidential debate stage, Sarah Palin, eulogized Beau Biden, the former Delaware attorney general, as a son, brother, husband and father and Iraq War veteran in a Facebook posting.

South Carolina Sen. Lindsey Graham, one of the Obama administration's top foreign policy critics, said on Twitter than Beau Biden's death was "heartbreaking and devastating."