This editorial first appeared in the The Arizona Republic.

In a life in which there is nothing left to prove, came one more catastrophic challenge Wednesday night.

“McCain has brain cancer,” roared the CNN home page.

On every news front in America, the same words told you the gravity of the moment: One of the world’s most powerful men is severely ill.

That brought all the other powerful people bearing tributes:

“Cancer doesn’t know what it’s up against. Give it hell, John.”

- Former President Barack Obama

“Senator John McCain has always been a fighter.”

- President Donald Trump

“John McCain is as tough as they come.”

- Former secretary of State Hillary Clinton

“Cancer picked on the wrong guy.”

- Vice President Mike Pence

Then Meghan McCain stepped in.

But it was shortly after 5 p.m. Arizona time that another tribute emerged on social media in words both moving and elegant from a daughter, who said:

“It won’t surprise you to learn that in all this, the one who is most confident and calm is my father,” wrote Meghan McCain.

No, Meghan. We’re not surprised.

Fifty years ago, John Sidney McCain III faced perhaps the most impossible odds of his life: That he, a 31-year-old Navy aviator, would ever measure up to the McCains who came before him.

Both his father and his grandfather were four-star admirals in the United States Navy.

And things were not starting out well for John.

None of this ever broke McCain.

In July of that year, 1967, John McCain barely escaped with his life when an electrical malfunction discharged a rocket and set ablaze the aircraft carrier USS Forrestal. One-hundred-thirty-four Americans would die that day.

In October 1967, McCain flew his A-4E Skyhawk in a bombing mission over Hanoi and was struck by a North Vietnamese missile. He ejected from his aircraft, breaking both arms and a leg. He then nearly drowned parachuting into Trúc Bach Lake.

The Vietnamese who found him stabbed him with a bayonet and crushed his shoulder with a rifle butt.

He would be taken to the Hanoi Hilton, where his captors continued the beatings and refused him treatment. It was the beginning of six years of imprisonment, in which he was routinely tortured and paraded about as an object of propaganda.

As the son of a high-ranking admiral, he was given the opportunity to skip the line and go home early. But he refused. He would not benefit from some other American’s misfortune.

He would survive the war, return home and become one of the most influential leaders of our time.

‘It will not make him surrender’

He has been through the political gauntlet time and again, including a grueling run for president in 2008. And still he managed to stay vital and win a sixth term in the United States Senate at age 80.

So you understand why Sen. McCain is calm.

“He is the toughest person I know,” wrote his daughter. “The cruelest enemy could not break him. ... Cancer may afflict him in many ways. But it will not make him surrender. Nothing ever has.

“My love for my father is boundless, and like any daughter I cannot and do not wish to be in a world without him. I have faith that those days remain far away.

“Yet even in this moment my fears for him are overwhelmed by one thing above all: Gratitude for our years together and the years still to come. He is a warrior at dusk, one of the greatest Americans of our age, and the worthy heir to his father’s and grandfather’s name.”

The McCain legacy is in good hands.

What father could read those words and not be moved to tears.

No one knows how this remarkable story ends. Our prayers and undying admiration are with John McCain.

But a new McCain has emerged with poise and eloquence and, yes, her father’s guts. No matter what happens now, John McCain must know his legacy stretches well beyond his years.

And a daughter faces the same daunting challenge her father confronted half a century ago — living up to a name that is splashed in grandeur.

John McCain is calm. But he is also, no doubt, warmed by the knowledge that his name and his legacy are in good stead.