Sen. John McCain (R-Ariz.). (Jacquelyn Martin/Associated Press)

John McCain’s mother’s name is Roberta. She is 105. When I met her, she was somewhat younger and something of a mythical figure to those who knew her son. He had often told about her trips through Europe and Asia by car while in her 90s, and so one night at a party John McCain was giving, I approached her, wanting to know more about her. I asked how she had weathered the five years her son had been a POW in Vietnam. She brushed it off. “We’re Navy,” she said.

She need not have said any more.

Sen. John Sidney McCain III (R-Ariz.) is the son of a four-star admiral. He is the grandson of a four-star admiral. He himself rose to the rank of captain, and as a Navy aviator he was shot down over Hanoi during the Vietnam War, was imprisoned and suffered two years in solitary confinement. When he ejected from his plane, he broke a leg and both arms. On the ground, he was bayoneted. At first, he was denied medical treatment and then, when it was offered, it was rudimentary. He was repeatedly tortured, beaten every two hours, wracked with dysentery. The North Vietnamese wanted him to accept release, but he refused. The military had its rules: First in, first out. McCain would wait his turn even if it cost him his life. He tried suicide, but finally he broke. He made a propaganda recording .

Now McCain has brain cancer of the worst kind. The prognosis is not good, and for me to write otherwise would violate the McCain spirit. His campaign bus for his presidential campaign in 2000 and 2008 was called the Straight Talk Express — and it was. I climbed aboard it in New Hampshire and before I knew it, we were in California in 2000. It was the ride of my life, hours siting with McCain and sometimes one of his old prison-camp buddies from Vietnam, and talking politics and government and history and books and movies and, even, gossip about some movie star. The bus rolled on, reporters got on and off — I did not stay the whole time — and one by one they became entranced, sometimes having to admit to a crush.

I’d sit next to McCain and try to take his measure. As a journalist, I deal in fame, occasionally in greatness. Sometimes I size up these people and wonder if I could do what they have done or, often, whether I would even want to. I am not as smart as some of them, nor as articulate, nor as disciplined, nor as ambitious, but mostly they do not awe me. McCain does. It is not merely that he went into combat — this is the great “what if” of most men — but he withstood torture, accepted it, really, as the price of service, which he had chosen. He could have said “Stop! Send me home,” and the North Vietnamese would have done so, crowing about the admiral’s son . . . and his shame. The last was the nub of it: shame. Horror of it is what motivates McCain. Pride is what animates him.

Now I hear McCain whispering in my ear. Don’t go there, Cohen. But I must. I have to compare McCain with that drizzle of apparatchiks who now populate Washington, that coterie of sycophants who have gathered around President Trump, to sing his praises and extol virtues that don’t exist. Can you imagine McCain doing such a thing? Can you imagine the man who preferred death to shame telling that playground bully Trump how great he is? It’s not that McCain is not a politician — in the most understandable of political triage, he briefly endorsed Trump, after all — but generations of McCains, Navy men and Annapolis graduates, sit on his shoulder. He cannot disappoint them.

McCain has his tics. His temper is famously volcanic. He is sometimes too ready to fight. Choosing Sarah Palin as his running mate in 2008 was more than a mistake. It was — as he must know — shameful. He loathes lobbyists with a fury that both impressed and intimidated me. To him, they are beseechers, beggars in Gucci.

McCain’s cancer is called glioblastoma, an aggressive brain tumor. It was what Sen. Edward Kennedy and Beau Biden, the son of the former vice president, both had. The outlook is grim, so now is the time to write. John Sidney McCain III — warrior, POW, senator, former presidential candidate and just plain swell company — will win this fight against cancer if anyone can. But if it is otherwise, Washington will have lost something of painful rarity: a wholly honorable man.

Read more from Richard Cohen’s archive.