That which does not kill us makes us stronger.

–Friedrich Nietzsche

Pain is weakness leaving the body.

–Familiar U.S. Marine Corps recruiting slogan

Nietzsche, the German philosopher/poet who died in 1900, would not seem to have much in common with, say, Gunnery Sergeant Tom Highway, the crusty, battle-tested leatherneck played by Clint Eastwood in the 1986 cinematic ode to the USMC, “Heartbreak Ridge.”

But Nietzsche and some Marine recruiter with a high-and-tight haircut and combat ribbons on his uniform aren’t as dissimilar as might appear at first glance. There is a little bit of each within the complex, enigmatic and fascinating mind and heart of the great Argentine boxer, Sergio “Maravilla” Martinez.

Perhaps Martinez, 39, is not the fight game’s ultimate mystery man, but even now, 17 years after his professional debut and 55 bouts into a brilliant career that appears to be winding down, he remains curiously distant to American fight fans who apparently prefer headliners who speak fluent trash and enter the ring with the clear, easily understood intention of knocking the snot out of their opponents. A lot of us, it would seem, prefer our favorite boxers to be cartoon characters with mean streaks and a penchant for violence to some South American-born, European-based Renaissance Man who offers only fleeting glimpses into the deeper recesses of his hidden self.

Martinez (51-2-2, 28 KOs), who defends his WBC middleweight championship against three-division former titlist Miguel Cotto (38-4, 31 KOs) on June 7 in Madison Square Garden (the fight will be televised via HBO Pay-Per-View), by no means presents a simplistic, paint-by-numbers image. Perhaps that is because he does not speak English, his more esoteric thoughts filtered through a bilingual interpreter who feeds Cliff’s Notes versions of his responses to basic questions from American media members who, for the most part, wouldn’t know or care about the difference between Nietzsche’s treatises on the creative mental powers of the individual and the raw, destructive punching power of a Mike Tyson or a Rocky Marciano.

(Check out this insightful video of HBO’s Harold Lederman talking about the manner in whcih Sergio fights, and the upcomingscrap vs. Cotto.)

So at this point really knows what it is that spurs Martinez to continue torturing his oft-injured body to continually rise to the sort of heights that someday will bring him induction into the International Boxing Hall of Fame. Is it a belief that his dedication to his craft is so absolute that he can will away the effects of multiple surgeries and other maladies that occasionally reduce him to near-handicapped status? Is it public affronts to his dignity that crop up more often than other champions of similar accomplishment?

But while Martinez’s motivation to keep on keeping on remains shrouded in intrigue, at least some answers will be provided on fight night, where certain truths are always revealed. Either Martinez remains one of the top four or five pound-for-pound performers in his brutal profession, his skills not noticeably ebbed by his advancing age or his litany of damaged body parts, or he will show himself to be on a steep downward slide that not even his steely resolve and once-formidable skills can brake.

For now, even Martinez and his handlers seem to be sending out mixed messages. Is Martinez – who again is living in Madrid, Spain, a shining jewel of European culture that seemingly fits his reserved personality more than did his dirt-poor hometown of Quilmes, Argentina, and his former U.S. residence in gritty Oxnard, Calif., as revived and refreshed as he claims to be? Or is he irrevocably damaged goods, soon to be brought down more by the relentless march of time and physical wear-and-tear than by the capabilities of a Cotto or any other high-quality opponents who may yet fill his dance card?

Listen to Martinez, and those affiliated with him, do the old two-step when asked about how the fighter’s lengthy layoff – he has not fought since scoring a unanimous, 12-round decision over England’s Martin Murray on April 27, 2013 – has affected him.

Martinez: “My knees are feeling great. I’ve been running in the morning, on the treadmill. I haven’t felt this good in a long time. I am the same that I was when there was no knee problems.”

Longtime adviser Sampson Lewkowicz: “If he’s not 100 percent, he’s 99 percent. He’s not 80 or 85 percent, or even 90 percent.”

Promoter Lou DiBella: “I believe his (left) knee is as good as it was before the (Julio Cesar) Chavez (Jr.) fight. I believe he’s in great shape. I saw him train in Florida and I was really pleased to see certain things I haven’t been able to see before some of his other fights, when his injuries were really bothering him. I saw great lateral movement. I saw able to plant his legs and throw with real authority and power. I think the year off to rehabilitate, to strengthen his body as opposed to taking a toll on it, is going to be a huge plus for Sergio, for his elbow, his hand, for everything that’s ever ached him.”

Yet …

Here is Martinez again, talking about that year off as something other than a needed vacation that presumably improved his health. In a recent interview with Lem Satterfield of ringtv.com, he admitted that, “It is not easy to prepare for a fight when you have some of the ailments that I have when preparing for a world championship fight. I struggle with joint pain, knee pain and shoulder pain. Because I train six days a week for an average of eight hours a day, I am always in constant pain. There are some days when I am so sore I cannot even walk, but I push myself because I know that I have to push myself to be the best fighter in the world.”

Even during this week’s teleconference with the international media, Martinez’s more optimistic references to his present physical condition were tempered by the acknowledgment that some things, when broken, are not so easily restored. “The rehabilitation was very painful,” he said. “I was on crutches for nine months. It was very hard to come back from that. I’m always coming back from some things like this.”

There are other “things like this” that Martinez has had to overcome, and will have to overcome against Cotto as well. It was noted by some reporters that Martinez, who almost always is at least somewhat complimentary toward his opponents, has shown a slightly more abrasive side of himself to Cotto, the popular Puerto Rican who has fought nine times in the big room at Madison Square Garden and filled the place each time. It is likely that again will be the case on June 7, when the Garden again will be a hotbed of Cotto partisanship.

In what cannot be viewed as anything other than a slap to boxing tradition, as well as to Martinez, Cotto, the challenger, will be introduced after the champion. And it isn’t the first time such disrespect has been directed at Martinez; it also happened on Nov. 20, 2010, when Martinez defended his WBC middleweight title in Atlantic City’s Boardwalk Hall against Paul “The Punisher” Williams, who had defeated him via 12-round majority decision on Dec. 5, 2009, also in Boardwalk Hall. For the rematch, Cotto had to endure the indignity of being introduced before the challenger.

Martinez issued the most resounding of rebukes to that perceived slight, knocking Williams colder than a January night in Siberia with a perfectly timed left cross in the second round. So concussive was the force of that blow, which landed flush to Williams’ right cheek, that Williams pitched forward onto his face, not even attempting to break his fall. Referee Earl Morton didn’t even bother with the formality of a count.

“That punch,” said DiBella, who provides most of the tastier sound bites that the enigmatic Martinez is unwilling to dispense, “would have knocked anyone on earth out.”

The wipeout of Williams, coming on the heels of his one-sided points dethronement of WBC/WBO middleweight champ Kelly Pavlik, was enough to vault the previously little-known (at least in the United States) Martinez into stardom. He was named the 2010 Fighter of the Year by both the Boxing Writers Association of America and The Ring magazine.

“He’s the best pure athlete I’ve ever promoted,” DiBella gushed after Martinez had sliced up Pavlik’s bloodied face as if it were a very rare steak. DiBella also marveled that he was able to “discover” Martinez, who had been a competitive cyclist and soccer and tennis player in Argentina, in 2007 after several other American promoters took a pass on a fighter who had fought almost exclusively to that point in his homeland and adopted home in Spain.

But boxing stardom is not the same as superstardom, which seldom is based solely on talent. Between Pavlik, Williams II and now, Martinez has been egregiously stripped of his WBC title by the Mexico City-based sanctioning body’s president-for-life, the now-deceased Jose Sulaiman, who more or less handed that title to the son and namesake of Mexico’s all-time favorite fighter, Julio Cesar Chavez. His anger at that injustice – and make no mistake, it was an injustice – was on display the night of Sept. 15, 2012, in Las Vegas’ Thomas & Mack Center, when he retook the WBC 160-pound that was rightfully his on a frightful beatdown of JCC Jr. The scores were 118-109 (twice) and 117-110.

But it was indicative of Martinez’s mindset, and the large chip he carried on his shoulder, that he was still trying to knock out Chavez in the 12th and final round. In doing so, Martinez was floored and badly hurt in the final minute of a bout he had been winning with ridiculous ease. Had there been another 20 seconds for Chavez to fire and land more desperation shots, Martinez might not have made it to the final bell.

“His (left) hand was broken, he got knocked down, his (right) knee was messed up, but he got up and didn’t look to hold,” DiBella said of Martinez’s refusal to play it safe when that was the more prudent course of action. “He looked to fight. Sergio Martinez is a man’s man.”

He is a man’s man with his let ’er rip ring style, but he is a thinking man’s man, too. In an interview with the New York Times, DiBella allowed that Martinez is “Cerebral. Sensitive. Very artsy. Likes fashion. Has his own sense of style, which is extremely Euro.”

In other words, the ruggedly handsome Argentine is as much a candidate to grace the cover of GQ or Time as a boxing publication. He is, as Winston Churchill once said of Soviet Russia in 1939, “a riddle wrapped in a mystery inside an enigma.” As such, he always seems vaguely inaccessible, a puzzle with many pieces, not so easy to figure out for the public’s convenience. Those who do not fit preconceived notions tend to stand out, but sometimes not in ways that guarantee widespread acceptance.

So this question was posed to Martinez, and to DiBella, who must have regarded it with a certain degree of incredulity: Does Martinez need to beat Cotto to gain “universal acceptance” as an elite fighter?

“He already has it,” DiBella said, likely with the understanding that some fights are not always won inside the ropes. Establishing a firm grip on a boxing buff’s undying devotion is not as simple as delivering a crushing left to the jaw. Nobody can really say they were drawn to Tyson because he is said to have read Machiavelli while he was incarcerated for his conviction of raping that beauty pageant contestant in Indiana.

Tossing around the heft of his popularity, especially in New York, Cotto sought concessions from the Martinez camp that went beyond who was to be introduced last. Some were of relative significance, others less so. The contracted weight limit demanded by Cotto, who has held titles at 140, 147 and 154 pounds and who had never fought above 154, was 159, one less than the middleweight limit. Martinez agreed to the demand, which he described as “annoying.”

“This was not an easy negotiation,” DiBella confirmed. “We kept having to call Sergio with more and more concession demands (from Cotto) that a champion generally does not have to give in to. He was not pleased. I think that came out at some of the press conferences. But I think he’s channeled that to his benefit. Right now he’s fixated with giving Cotto a beating and walking out of Madison Square Garden as the middleweight champion.

“Sergio wanted Miguel Cotto. He wanted this fight badly. He’s always wanted to fight in the big room in Madison Square Garden before he retired. In order to get that fight, we had to swallow some stuff we didn’t want to swallow.”

We shall see whether Martinez can make Cotto swallow stuff right back, most likely in the form of a ripping left that would put his antagonist down and out. But nothing can be certain at this point; not only is Cotto, 33, still very capable, but Martinez is a question mark given his age, his inactivity, the fact he has been dropped in each of his last three fights, and, of course, his laundry list of injuries: knee, hand, wrist, elbow, shoulder.

If Martinez is at near-peak efficiency – or if he can ignore the discomfort of his more chronically balky body parts – he should win. But saying, and wishing, that something isn’t so has never meant much when the determined guy in the other corner is trying his hardest to beat the mystery out of your enigma.

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