Dustin Johnson’s second-round 67 at Shinnecock Hills left him with a four-shot lead and as the only player under par. (Justin Lane/Epa-Efe/Shutterstock)

Let’s take a tour through the golfing mind of Dustin Johnson, the top-ranked player in the world. It’s a much longer trip than I once would have suspected.

Johnson, whose second-round 67 at the U.S. Open on Friday left him with a four-shot lead and as the only player under par at Shinnecock Hills, is an acquired taste. And though it has taken a decade, I have acquired it.

For generations, many of the greatest golfers have had sophisticated theories of the proper swing or offered dissertations on tactics and course management. Many are fascinated with the psychology of coping with the game’s constant frustrations. We’re told constantly that the most important few inches in the sport are the distance between a player’s ears. So we think it’s the brain game.

Bobby Jones had degrees in law, engineering and English literature. Ben Hogan’s “Five Lessons” was so brilliant it’s still an excellent instruction book.

From analytical Jack Nicklaus to curious, creative Tiger Woods, as well as Tom Watson, the Stanford psychology major, and Phil Mickelson, who has a separate theory about every groove on his 60-degree wedge, golf tends to attract and reward the studious types. Jordan Spieth, who already has won three majors at 24, impresses — and sometimes intimidates — his foes with his “golf IQ.”

So, at times, there may be a subtle prejudice within the game against granting the highest respect to top golfers who are normal people — not obsessed with technique, terminology or breakthroughs in equipment technology.

If a fellow such as Johnson is a superb athlete, likes to compete, is not deflated by brutal losses or even repeated bad luck in majors, does he really fit in the game’s tradition of players who are as impressive when they talk as when they swing?

If Johnson is also, probably, quite happy, with a glamorous wife and two young children, if he is unlikely to dive into months of despair over losing a golf tournament, is he really taking the game seriously enough? Shouldn’t he suffer?

This week, it has clicked for me — probably long after it has for lots of readers — that Johnson is a regular guy who doesn’t want to inhibit or even ruin his gifts by analyzing his game to dust. He may not discuss The Swing as well as Justin Thomas, No. 2 in the world, but Dustin sure understands his swing — the one with a backswing far past parallel that lashes the ball incredible distances.

Think of Johnson as a fabulous, sleek feline athlete who, in a great break for golf, chose a game that is frequently played by people who hope to drive Jaguars but seldom by men who look like one.

Since Johnson, 33, knows himself and seems comfortable, he often slyly plays off his image as the laconic primitive, eyes shrouded under his pulled down cap. Are you in there, Dustin? What time’s your wake-up call today?

Early this week, Johnson was asked to compare and contrast himself with Thomas, the man who took over the No. 1 spot from him for a month before Johnson took it back with a win last week in Memphis.

“I have no idea,” Johnson said, pleasantly.

“Maybe, just, hoping you’d throw something out there,” the reporter said, sorry to have been a bother.

“We’re both very good golfers,” Johnson offered by way of comparison.

Then, for contrast, Dustin added, helpfully, “Our height.”

And, indeed, Johnson is six inches taller than the 5-foot-10 Thomas.

Minutes later, Johnson was asked what goes through his mind at the instant of contact. Where the ball should go, perhaps? Or some technical swing thought?

“Good question,” Johnson said. “I have no idea. When I’m actually hitting it, I’m not really thinking about anything. Never really thought about it, though.”

“Don’t start,” the interview moderator interjected.

“I’m not going to,” Johnson said.

After his impressive 69-67 start here on a course where Woods, Rory McIlroy, Jason Day, Sergio Garcia and Jon Rahm missed the cut, Johnson was asked about the frustrations of playing in the U.S. Open, the fury it roused in so many players. In Johnson’s case, when had he, most recently, been angry on a golf course?

“Last week,” Johnson said, an amusing thought since he won his previous event by six shots and holed out for eagle from 170 yards on the 72nd hole. “I don’t get too angry. I hit bad shots all the time. Why am I going to get upset? I do it every day that I play. So you just got to go find it and hit it again.”

With the world golf press, desperate for any hint of “human interest,” now reduced to whimpers, one final attempt was made to tempt Johnson into self-destructive introspection: When did you last throw a club?

“I don’t throw clubs,” the best player in the world said. “It’s not the club’s fault. I wish it was, but it’s not. . . .

“We’re trying to set an example for kids. So no matter how mad I get, I’m probably not going to show you, and I’m definitely not going to throw a club.”

Johnson may have “only” one major title (the 2016 U.S. Open) and two runner-up finishes in 35 starts in major championships, but the resilience he has shown, finishing in the top 10 in 14 majors, is remarkable considering the blows he has suffered from the game or from himself. Given his opportunities from 2010 until now, none of his peers would be surprised if he had won three or four majors.

A few snippets from his history:

●Johnson led the 2010 U.S. Open by three shots before an 82 on Sunday. That would have unhinged some players for years.

●He missed a three-way playoff in the PGA Championship that year because of a two-stroke penalty on the 72nd hole for grounding his club in a bunker — a bunker that almost no one knew existed. A man inclined to curse the fates — or officials — could have felt hexed.

●He missed the 2012 Masters because he hurt his back lifting a jet ski.

●He came into Augusta last year red hot, then missed the tournament when he slipped coming downstairs while wearing socks in his rental home, smashing his elbow.

●In 2015, he three-putted from 12 feet on the 72nd green to miss out on both a straight-up victory and then a three-way U.S. Open playoff. Did he grasp the message of the scoreboard as well as others? If he was going to fold on I’m-a-big-dope grounds, he would have done it then. He didn’t.

●The same year, at the British Open, he was ahead and dominant, as he has been this week, then shot 75-75 on the weekend.

And he took off nearly half of the 2014 season to seek professional help for “personal challenges,” perhaps the result of too much partying.

Despite all this, Johnson blames nobody for anything, maintains a calm but upbeat disposition and doesn’t view himself as snake-bitten. He just keeps showing up, constantly putting his name near the top of almost every leader board.

After some fabulous hole-out shot, such as a bunker blast for a birdie here Thursday, that might send other players into a dance, Johnson is likely to raise one hand to acknowledge the crowd but save his big sincere grin for a playing partner who says something funny or friendly. Then he looks as happy as my dog getting his stomach scratched.

The biggest stages seem natural to him now. Asked how he will “sleep on the lead” going to the weekend, the laid-back Johnson brought a laugh, saying, “I usually don’t have any trouble sleeping.”

When you watch Johnson try to close the deal on his second major title this weekend, remember that, titanic as he is and as unbeatable as he looks when he’s on a roll, he has his golf demons, too. His spells of genuinely bad putting seem to appear from nowhere. And the sudden brain-numbing double or triple bogey from hell, much as he focuses on avoiding it at all costs, still shows up.

“I’d love to get that second one, but everything’s got to work well for four days,” Johnson said. “The game is not easy, that’s for sure. . . .

“As I get older, I want to make things as easy as possible,” Johnson said, “even though they don’t get any easier.”

Sounds pretty smart.

For more by Thomas Boswell, visit washingtonpost.com/boswell.