When I was in junior high, at the Eaglebrook School in the green hills of Massachusetts, I read a book about John F. Kennedy that said he used to carry an anonymous poem with him in his wallet:

Bullfight critics, ranked in rows,

Crowd the enormous plaza full.

But only one is there who knows,

And he’s the man that fights the bull.

I loved that quote. I carried it in my own wallet for years, well through college, until that wallet was lost when I flipped the dinghy during a hurricane in Bermuda. I wanted to be the one who knows.

I grew up romanticising fighting and fighters. After high school, I joined the merchant marines. I took the 3am train from an unmanned station in Amherst down to Maryland, to the Seafarers Harry Lundeburg School of Seamanship. When my mom dropped me off, in a pool of light from a street lamp at the deserted station, with my dad’s old navy duffel bag, I was a living Norman Rockwell painting.

The school was run like a boot camp – shave your head, shine your boots, do push-ups till you puke – and my “class”, number 518, started out with about 28 guys and finished, four months later, with 13. Some of this was due to racial tension; the class was half white and half black, and there were some fights. The black guys, it seemed to me at the tender age of 18, had a better handle on how to deal with the pressure, and the endless work: they did just enough to coast through, while the white guys were killing themselves trying to complete the Sisyphean tasks put to us by an unusually cruel bosun. I found a way to live in both worlds, and I learnt one of the most important lessons in life: keep your mouth shut. It was my introduction to the world of tough guys.

Half of the class had been in jail for one reason or another, and I told no one about my prep school background or Ivy League future. One of my best friends there had a spiderweb tattooed on his face, right under his eye. I dared him to cut my hand off one night on the meat slicer, laid my hand on it, stared him in the eye, and said, “F*** you, do it” (everybody had to talk that way). He gave me a small, tight-eyed look and then looked away.

A few years later, an art critic named Peter Schjeldahl, who was teaching at Harvard (I was an art major), said to me, “You’re wondering what all young men wonder: am I a coward or not?” That was part of it, though I knew I probably wasn’t a coward. Bravery is something different. Bravery has to be proved.

At Harvard I tried t’ai chi and tiger kung fu, and one day I happened upon the boxing gym, where Tommy Rawson was the coach. He was about 4ft 5in and maybe 80 years old. He’d been a professional fighter in the Thirties, and he was magical. Finally, here was real fighting and sparring, with headgear and a mouth guard and big 16oz gloves. Tommy couldn’t remember anyone’s name, but he understood boxing in his bones. “Hey slugger, don’t start weaving until he gives you trouble,” he’d call in a harsh voice that had yelled out things like that for 50 years. He always had a gleeful smile on his handsome, crumpled face.

Sparring with headgear comes as a revelation, because you get hit and it doesn’t really hurt. It becomes like a chess match: you think, hey, he jumped back when I did this, so next time I’ll fake this and actually do that and then you have the satisfaction of burying a hook to the side of his head. There is the battle rage that is so enthralling, the berserker emotion that doesn’t discern friend from foe but simply rejoices in blood. This was the feeling I was after. My adrenal glands were triggered and I was fully engaged in the moment: someone was trying to kill me. The door opened on a new world.