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The Temptation of 10,000 Hours

To make an effort is to work at odds with oneself

ALAIN

Ease, or “facility,” is not a concept—it’s a feeling. A feeling we have, or can give. At primary school, I was said to have “facilities,” because I liked reading. I loved it. In the last two years of primary school I read at least a book a day. There was nothing praiseworthy in this: it was like eating sweets or being given a reward—it was literally a piece of cake. I saw my friends struggling to read one book a week, while there I was, having a great time knocking back a couple a day. Sometimes I’d read the same one twice. I remember, I read The Call of the Wild three times in one day, each time faster than the last. I loved the story of the dog, Buck, who is kidnapped, and overnight goes from the easy existence of a domestic dog to the cruel life of a sledge dog. Despite his “bourgeois” origins, Buck has an advantage over the other dogs: he enjoys dragging the sledge and fighting to be first. For the others it’s an effort but for him it is a joy. It comes instinctively, hence the title of the book. The others suffer, but for him it is painless, it’s the call of the wild. For me it was the call of the book. There was nothing laudable about Buck, nor about me. We were both doing what we loved most in the world.

A few years later, when I was in advanced math, I realized what it was like to be on the other side. The lesson went so fast I got a pain in my wrist just from taking notes. After two relentless hours of copying down symbols and equations I didn’t understand, I felt like a donkey going around in circles, attached to an endless turntable, producing nothing but a feeling of futility. Or like Sisyphus, who Albert Camus said we must suppose is happy, even though he is condemned by the gods to push an enormous boulder up a hill, watch it roll back down, and push it back up again for all eternity. Once the day’s lessons were over, the real day began: each of us, in our dormitory room, sweated over the exercises for the following day. All the “molies” “delved.” “Molies” (the image speaks for itself) in “mole class” (advanced math) dug away, never seeing the light of day. “To delve”—the word has a flavor of medieval labor. After all, we were in the university quarter, at Louis le Grand lycée, and it was meant to be hell. Well, not for everyone. There were a few people for whom it was a walk in the park. Cédric, for example, who never “delved” and spent his life wandering in the corridors. A “mole” would stick his head out of his hole and hand him a piece of paper saying: “Cédric, I’ve been doing this for two hours, it’s impossible.” Cédric would glance at it, do a quick turn up and down the corridor, and a minute later would say with a smile: “There are two solutions. The second one is more elegant.” He hadn’t made any effort. He’d just seen the solution. Solutions, even. Where others looked without finding even one, he found two without even looking. Math was in his blood, it was his call of the wild. Once I’d seen that, I didn’t hesitate: I returned to my own calling. The headmaster was happy for me to take my classes preparing for the École Normale Supérieure in the humanities stream, or khâgne, as it’s called, a French reference to the knock-knees of people who spend too much time reading. Going from being a “molie” to being a khâgneux was not going to change how much sport I got to do a week, but in any case I was going home, back into my element. The teacher simply remarked: “I told you so.” He knew what he was talking about.

After only two weeks of advanced math, I already felt tired, empty, short of energy, exhausted before even starting the race. From the moment I knew I had got into the humanities stream I sprang back to life, once again full of energy, enthusiasm, and joy. Not for long, obviously, since the “preparatory class” is still essentially an ordeal, but the first few days were euphoric. I understood what was written on the board; the teachers were speaking my language again. Everything was back to normal, and although the general atmosphere was stressful, understandably so in a class aimed at preparation for an exam, I felt like I had escaped from prison, or slipped away from the hell of forced labor, and could once again look out onto wide open spaces and all the possibilities they contained.


I rejected the suffering that comes from pursuing a path to which one is not suited. Effort against the grain is exhausting. It’s a sign of courage and of abnegation, but above all it’s a sign of self-deprivation. A negative virtue is not without value, but in the end someone who doesn’t like what they do will never go as far as someone who enjoys it. The former will do everything on sufferance; the latter will do it with joy, including suffering if necessary. A characteristic of a good sledge dog is that he enjoys pulling a weight for hundreds of kilometers. You don’t have to push him to do it. Eric Morris, a specialist in these matters, explains that to train sledge dogs to go very long distances, as in the Iditarod, known among enthusiasts as the “last great race on Earth” (over 1,500 kilometers through the cold, long nights of Alaska), there’s no point in using food as a reward. Negative reinforcement, a training technique that consists not in giving a reward but in taking away a punishment, doesn’t work either. “To go that distance, it’s like a bird dog sniffing down a pheasant . . . it has to be the one thing in their life that brings them the greatest amount of pleasure. They have to have the innate desire to pull [the sledge] . . . and you will find varying degrees of that in different dogs.”

When I read that in David Epstein’s excellent book The Sports Gene, my first reaction was to bay for blood, or rather to howl at the moon. I was shocked by the link he made between rearing sledge dogs and training high-level athletes. When people suggest naively that you just have to want something in order to succeed, Epstein replies, on the basis of sound research, that it’s not that simple. Some people can do things even if they don’t want to, they don’t have to try, nor even to make a decision: they have no choice, they just have to run. He takes the example of Pam Reed, an ultrarunner who participates in events such as the Badwater Ultramarathon, a 135-mile race starting in California’s Death Valley, which she has won twice. She explains that if she doesn’t run at least three to five times a day, for a total duration of at least three hours, she doesn’t feel good. As she gets older, she manages to stay still for longer periods of time, but she still finds sitting uncomfortable. Françoise Sagan is the same, but with reading. The writer, who published her most famous work, Bonjour Tristesse, when she was just a teenager, says: “I read all the time, even when I’m writing. When I’ve been working for several hours without a break, I take a rest and read for a bit. Handing over your thinking to someone who’ll think for you, especially if the book is really gripping, is the best kind of relaxation for me. I love it, and it makes me feel optimistic.” I am sure that for Cédric, a day without math is equally unimaginable. None of these cases has anything to do with will, or scarcely anything; no effort is required, in the disagreeable sense of the word. Sagan, whether she is reading or writing, is in her element with words. Cédric’s not just in his element with mathematical problems, he’s wallowing in it. Both of them are like fish in water. Or rather like sledge dogs in the cold and snow. This is a better image, because even when it’s hard for them, they love it. They love dragging their sledge. That’s the difference.

Whenever I’m able do something without any effort I start to think it is inherently easy, that anyone should be able to do it. This is called the expert’s illusion. The minute you find yourself on the other side of expertise you realize it is an illusion, and that what is easy for one person isn’t necessarily easy for another. You find the illusion of the expert with literature teachers who think everyone must love reading. Or with math teachers who can’t understand why you don’t understand. This is the only thing they find difficult: understanding that what is easy for them is difficult for others.

The inverse also exists—thinking that because something looks easy for others, it will be easy for me. This is the illusion of the beginner. Just because you’ve seen Philippe Petit walking effortlessly on a rope doesn’t mean you can do it yourself. And watching Cédric solve a math problem in thirty seconds doesn’t mean you’ll be able to do it too, through contagion. Generally speaking, it becomes clear pretty quickly: the beginner’s illusion does not survive the experience of reality. But there is still such a thing as beginner’s luck, the luck you have when you manage to do something difficult at your first attempt, precisely because you don’t yet realize it’s difficult. The first time I touched a basketball, I tried, for a laugh, to put it through the hoop from the middle of the court, backward. Impossible, obviously. All the real players laughed at me. I threw the ball behind me, as far and as high as I could, and just had time to turn around to see the ball completing its perfect flight and passing through the hoop without touching the edges. Then I quit the court, nonchalantly, while all the players stared in amazement. I was pretty amazed myself; I knew I hadn’t done it deliberately and that I would never be able to do it again. Beginner’s luck, by definition, never lasts. The first time is magic; you are able to do amazing things that are then wiped out by your second or third attempts, but the memory can work like a promise: if you train for years on end, you might rediscover the luck, the innocence of the beginner. The expert is someone who has finally succeeded in recovering the state in which miracles happen, and which is properly called grace.

Grace is what Philippe Petit displays on the wire, or Zinedine Zidane on the soccer pitch. Anyone can see it. In the case of Zidane, even his teammates noticed it. Even the wives of his teammates, despite being surrounded by world-class quality: Victoria, the wife of David Beckham, Zidane’s partner at Real Madrid, compared him to a ballerina. It was a compliment—she herself was a dancer. But there is a fundamental difference between soccer and dance: the soccer player is not simply seeking to create a beautiful movement, he wants to win, and to do so he has to score goals. His movement has a purpose, while that of the dancer has no other purpose than itself. Nevertheless, dance and soccer do have something in common: the training is hard. Even for Zidane. Because it has a religious meaning, grace is a dangerous word. You might think it is a gift, that you either have or you don’t, and that there’s nothing you can do to acquire it. But believe it or not, Zidane worked very hard to achieve his state of grace. He had certain facilities, he was gifted, yes—but work was what allowed him to realize himself. For Philippe Petit, it was the same. He is happy to admit it: “I don’t have a net, but I’ve made a psychological net out of details.” Before hurling himself into the void between the Twin Towers, he put in the hours. He thought of nothing else for months. Piece by piece, with the patience of a medieval craftsman, he constructed his mosaic, this perfect moment. For a few minutes of grace, he spent years in preparation. He warns: “It’s a profession. Sober, harsh, deceptive. Anyone who isn’t up for a long hard battle, with wasted effort, extreme dangers, and traps, who isn’t prepared to sacrifice everything for the feeling of being alive, is not cut out to be a tightrope walker.” And anyway, they wouldn’t succeed. Does he have any tips? Simple: “Work, work, work. The wire has to gradually come to belong to you.” Only then, “after long hours of training, will the moment come when all difficulty falls away. Everything is possible. Everything feels light.” So, ease comes at the end. Not at the beginning. But after how many hours of training? “Don’t expect to get anything from one serious session of a few hours,” he warns. “It has to get under your skin.” When, in the days of Edith Piaf, you said someone had got “under your skin,” it meant there was nothing to be done, you had no choice: love is a yes or no affair, you can’t change it, that’s just how it is. Love at first sight is like friendship for Montaigne: “Because it was him, because it was me.” Friend or lover, you’ve got them under your skin. Or not. Whereas soccer, tightrope walking, violin, piano, dance, all activities that depend on expert gestures, have to be literally “incorporated.” Through toil, sweat, and time. Everyone knows work is necessary. You can’t go directly from the square that says “couch” to the one that says “champ” just by throwing a dice or saying some magic words. Even to be able to do magic, you have to go to school—just ask Harry Potter. The goal of all work is to acquire a second nature, which in the end will allow you to accomplish with ease what is difficult at first. All facility comes from surmounting difficulty. As they say in the military: “tough training, easy war.” There are no shortcuts. Isn’t what we call talent, when examined closely, really work, more or less concealed? And when we speak of genius, isn’t that really clandestine work? No one doubts the necessity for training, we can all agree about that—but the question is how much?

Remember Malcolm Gladwell? He’s a writer at the New Yorker, and I love reading his books. In Outliers, which here is used to mean “exceptional successes,” Gladwell gives a precise answer to that question “how many?” Ten thousand hours, according to him, is the “magic number of greatness.” You want to become exceptional in any given domain? It’s “easy”: you just have to devote 10,000 hours to it, or ten years, to become an expert or perform at a high level. Strangely enough, this is exactly the conclusion Stendhal arrived at: “Write every day for an hour or two. Genius or not.” Ten years of writing for one or two hours a day, somewhere between 3,652 and 7,304 (counting leap years) gets you close to 10,000 hours. You’d only need to write between two and three hours a day to get there. Stendhal seems to be saying, like Gladwell, that what we mistake for genius is simply the result of hard work; ten years’ hard work, to be precise.

Why ten years, when by working ten hours a day you’d get to 10,000 hours in a thousand days, which is less than three years? Because it’s not enough to accumulate hours of practice; the practice has to be deliberate, it has to represent an effort to achieve a specific goal, ability, or gesture that as yet eludes you. To put it another way, you need to feel the time passing, it needs to not be easy. This is quite different from the so-called ten hours a day spent by Zola or Flaubert, who seem like workaholics when in fact they spent most of their time dreaming of the right word, “fiddling around” with their sentences like Giacometti fiddling around with his clay; in short, doing what they liked best, which takes a lot of deliberately wasted time and a certain kind of nonchalance. Nothing to do with continuous effort, in any case. Three or four hours a day of deliberate practice, preferably spread out over several sessions, would therefore be a maximum, because the effort of all that attention is exhausting. The rest of the day should be spent resting, or in comparatively less intense activities: reading, reflection, strategy, associated leisure activities, and so on. Three to four hours a day with one day of rest a week, and two weeks of holiday a year, gets you to 1,000 hours a year, or 10,000 hours in ten years.

So it takes ten years to become an outlier. While we’re on the subject, notice the contradiction between the title of the book and its content, since by definition it is impossible to generalize on the basis of special cases. Even if an exception does occasionally prove the rule, it’s impossible to see how to establish any rule whatsoever on the basis of exceptions. But Gladwell proposes a “rule of 10,000 hours,” illustrated by examples like the Beatles or Bill Gates. If you think they’re geniuses, Gladwell explains, you’re missing the key part of their story. Essentially, genius is a concept invented by the lazy. It allows one to think that successful people only had to get themselves born, while in fact circumstances gave them the chance to become exceptional by giving them the opportunity to work more than others. In the case of the Beatles, for example, Gladwell tells us how their manager decided, when they were still a band with very little experience, to send them to Hamburg to play several gigs a day in dodgy clubs for months on end. By Gladwell’s analysis, what should have been an ordeal became an opportunity, increasing their experience and maturity, toughening them up and getting them to 10,000 hours while other bands who stayed in Liverpool or elsewhere in England only got to play for a few hours at the weekend. This competitive advantage gave them a head start of several lengths once they got back to England, and gave them their breakthrough. Bill Gates? Same phenomenon. At the time when he started to get interested in computers and programming, you had to wait a week to access the university’s one computer for even a few minutes. But his mother, who worked in a hospital, arranged for him to have access, every evening, to the computer in her workplace, which no one used at night. Bill Gates took his chance and clocked up hours of experience every day—or, rather, every night. This was transformed into a huge competitive advantage for him a few years later, when he entered the race in the development of personal computers. So you thought the Beatles were the Rimbaud of pop and Bill Gates the Mozart of computer science? Well, you were wrong—they were simply serious workers, hardworking artisans, maybe inspired grafters, but above all, they put in the hours. Besides, Rimbaud, on closer examination, that so-called genius poet and author of the famous line “No one is serious when they’re seventeen,” was actually extremely serious, and won the general Latin verse prize when he was only fifteen years old. Rimbaud, the classic outcast poet, all of whose work was written before the age of twenty, was above all a star pupil, and excellent at Latin, which he wrote fluently, without the need for a dictionary. If you add up the writing of his poems, his study of Latin, and his advanced reading, it must easily come to 10,000 hours. What about Mozart? Initiated into the subtleties of the harpsichord by his father at the age of five, at fourteen he could transcribe Allegri’s Miserere, a complex work that lasts a quarter of an hour, having only heard it once. Impressed? Add it up: by the age of fourteen Mozart had easily done his 10,000 hours, and more. Rimbaud and Mozart didn’t come out of nowhere; they just started early.

Ten thousand hours in ten years, I hear you say, OK, that sounds pretty good, pretty serious without being impossible—but how did Malcolm Gladwell arrive at this exact, nice round number? It all comes from a 1993 study led by K. Anders Ericsson (at Florida State University) and two other psychologists at the world-renowned music academy of Berlin. I’ll give you the gist: take thirty violin students, chosen by their teachers, and divided up into groups of ten in three categories: the “best,” the future international solo artists; the “good,” the future orchestral players; and the “less good,” classed as “future music teachers” [sic]. They all devoted 50.6 hours a week to studying music, whether in the form of theory lessons, practical lessons, concerts, etc. Apparently they all spent the same amount of time working on their instruments, but with one key difference: the first two groups spent 24.3 hours a week on private practice, i.e., working alone, compared with only 9.3 hours for the last group. Another significant difference: the violinists in the first two groups reckoned they slept about sixty hours a week, compared with 54.6 in the last group. So, more personal work, and more rest. Up to this point, there was still no difference between the “best” and the “good.” But when they were asked to estimate retrospectively how many hours of practice they had accumulated on the violin, it was then discovered that even if the first two groups did the same amount of weekly private practice, the best simply started younger. By the age of twelve, they already had 1,000 hours’ lead on the future teachers. At eighteen, the future soloists had done on average 7,410 hours of private practice, the good players 5,310 hours, and the future teachers 3,420. “So there is a direct correlation,” concluded the psychologists, “between the level of competence of the groups and the average total private practice time on the violin.” Since we see similar results with pianists, the researchers estimate that expert musicians, whatever their instrument, have, on average, clocked up 10,000 hours of practice by the age of twenty. Or to put it more precisely, I should repeat that that means “purposeful practice,” in which the players willingly apply themselves to difficult exercises that demand an effort, the kind of practice that by definition must be solitary, because it is high risk, and needs to be conducted away from the judgment of peers. In an article entitled “The Role of Deliberate Practice in the Acquisition of Expert Performance,” Ericsson and his co-authors extended their conclusion to sport. In sport, as in music, what we assume is a gift, an innate talent, is in fact simply the result of years of serious training. Based on approximations and generalization, this study, carried out on violinists, would go on to become the “10,000-hour rule,” according to which 10,000 hours are both necessary and sufficient to become an expert in any chosen field. The message is encouraging, democratic, and egalitarian, because it supposes that “you can if you want to,” and that hard work will take you as far as you want to go. But it has also led to an increase in early training for children, in sport as in music, and confirms the prejudice that says that if you don’t make progress in any given domain, it’s because you haven’t worked hard enough. The message both liberates (anything is possible) and blames (if you don’t succeed it’s all your own fault). The “magic number of greatness,” as Gladwell calls it, can easily be used to stigmatize.

Dan McLaughlin, having read Gladwell, took this number seriously and decided, on April 5, 2010, the day he turned thirty, to drop everything and devote himself to golf with the aim of becoming a professional at the end of 10,000 hours. In order for the experiment to be convincing, he needed to have no particular physical gifts, and to have never played golf. This was indeed the case. He describes himself as a completely average person. If it worked for him, it would work for anyone. He started a blog and set his plan in motion. He consulted with Ericsson himself, who drew up a timetable for him, and he engaged a professional golf instructor. Six hours a day, six days a week. Or, rather, eight hours, because he spent two hours thinking and analyzing, to give himself a break. Six hours a day is practically twice the “normal” pace. At that rate he should have finished his 10,000 hours and become a professional by the end of 2016.

But it wasn’t that simple. Even Ericsson acknowledged that his study involved too few subjects to be generalizable. In addition, they were subjects who had been both selected and trained. So it was impossible to differentiate between what was innate and what was acquired, what was due to talent and what was due to work. The study is constructed in such a way as to disregard anything that might come from natural talent. It is also a retrospective study, and the estimates given by the violinists varied by as much as 500 hours. Lastly, and most importantly, the 10,000 hours are only an average. On average, the best had worked for 10,000. But we don’t know the variance—that is, the degree to which the different subjects in the study were adrift of the average.

David Epstein, in The Sports Gene, puts his finger on this detail (which is more than a mere detail), and suggests we consider chess. Chess is different from the violin. Since players are ranked according to a system of international points—“Elo points” (named after the system’s creator)—one can know the exact level of a chess player, and follow their progression precisely. In 2007, psychologists Guillermo Campitelli and Fernand Gobet conducted a study of 104 players of different levels. An average player has around 1,200 Elo points. A master has between 2,200 and 2,400. A grand master has over 2,500. They saw that to reach the threshold of 2,200 points and become a professional took an average of 11,053 hours. A bit more than the 10,000 hours for musicians. Where it gets complicated is that according to individuals, the number of hours they have spent varies from 3,000 to 23,000. Twenty thousand hours’ difference, or twenty years of “purposeful practice”! Some people need to train for eight times longer than others to reach the same level. There are also players who tot up 25,000 hours without reaching master level. And there is no guarantee they will ever reach it.

It’s the same in sport. A study of triathletes shows that within the same level there are differences of a factor of ten. Some people had to train ten times more than others to reach the same standard. Moreover, with the same amount of training, we see what sociologists call the “Matthew effect,” named after the Gospel According to St. Matthew, in which it is said that to those who have, more will be given, and from those who have nothing, the little they have will be taken away. This is not quite correct, because training works for everyone, but far from compensating for natural differences, it simply deepens them irretrievably. The best become better more quickly than the good, and the others don’t even get a mention.

According to the rule of 10,000 hours, though, it’s the number of hours spent training that should explain the variations. Now, according to another study (also conducted by Ericsson, this time with darts players rather than violinists), after fifteen years of practice, only 28 percent of the variation in performance can be attributed to training. To put it another way, you can train your whole life without ever catching up on the difference between yourself and the best, or acquiring real expertise. The rule of 10,000 hours, David Epstein concludes, with some humor, would be better called the rule of 10,000 years.

In any case, putting in your 10,000 hours in your given area absolutely does not guarantee that you will reach expert level. You need both the innate “hardware” (the “cables,” the computer), which comes from nature, and the acquired “software,” which comes from training. To achieve greatness there is no magic number of hours that will allow you to substitute work for being gifted. You need both: the gift and hard work. The gift without the work will go uncultivated, the work without the gift will be sterile. In both cases, it’s a waste. It’s a pity not to train if you’re gifted, but training when you have no gift can be harmful. You may incur needless harm to your physique and to your ego, and tenacity or denial can turn into blindness and useless obstinacy.

Dan McLaughlin knows about this—he had to abandon his “Dan Plan” in 2015, following a back injury that forced him to interrupt his “purposeful practice,” and in fact his practice altogether. Accident? Tiredness? Somatization? The 10,000 hours literally weighed him down. His body said “stop!” after 6,000 hours. After two years of silence and denial, when he was on the verge of depression, he wound up his experiment in 2017 with a last message on the site he’d set up in 2010 to keep a record of his progress:

I apologize that this has taken me almost two years to write. It was never my desire to change directions and hang up the sticks. It was after having a heavy heart for a long time that I finally realized my own physical limitations and what I needed to do to move on in life. I did not even admit to myself that this was over until earlier this year and even then it seemed like I had not fully accepted the reality of it all. [ . . . ] I am not in any way happy to have had to hang up the clubs, but after having enough time to properly process everything I have come to realize that some things are out of our hands and it’s not about what you want to do in an ideal world, it’s about what you do with the circumstances that are presented.

True courage, for him, turned out to be recognizing his limits and his humanity, and renouncing his desire to be all-powerful. He discovered the Stoics’ precept that if we want to be happy, we need to focus on the things we can control, and leave the rest to the gods. In this sense his experiment taught him something, and his failure is a success, because he became aware of his own physical reality, and of reality itself. One point in his favor: it took only 6,000 hours for him to realize this and to become an expert in stoicism; that’s 4,000 hours fewer than predicted. That’s not counting the two years of doubt and denial, which makes 365 a 2 × 24 (since depression is twenty-four hours a day), equaling the 17,500 hours of “purposeful depression” that it took him to realize that the rule of 10,000 hours perhaps didn’t exist or wasn’t valid for him. The rule of 10,000 hours flatters us because it allows us to think that with enough work, we can become whatever we want. That everything depends on individual will and a sense of effort. If performance was only about training, if 10,000 hours really were sufficient to compensate for natural differences, why continue to separate men and women in competitions? Because, as David Epstein shows, just because we want to doesn’t mean we can. To think you didn’t become a golf champion after 10,000 hours because you didn’t work hard enough is as misguided as to believe that a champion doesn’t need to train, that they just have to exist to win. The temptation of 10,000 hours, for all its whiff of egalitarianism, offers an even more dangerous illusion than the inverse temptation to just let it all hang out. You can’t afford to skimp on training, nor to underestimate your limits. We shouldn’t say “if you want to, you can” but “if you can, you’re right to want it.”

Now it’s true that Zinedine Zidane was only twenty-six years old when he headed the ball into the goal twice in the 1998 World Cup Final against Brazil. Since he started out at AS Cannes at fourteen, he must have easily done his 10,000 hours. And the training sessions at Juventus, in Turin, where he continued his development in 1998, are famously tough. Zinedine had to sweat blood to become Zidane. And Philippe Petit, when he stepped out between the Twin Towers in 1974, was just short of his twenty-fifth birthday. Since the moment he started training, he must have clocked up more than 10,000 hours. And he had experience of great heights: in 1971 he’d walked on a rope between the towers of Notre-Dame. In 1973 he had done the same thing between the pylons of the Sydney Harbour Bridge, the widest bridge in the world.

But let’s ask ourselves simply and honestly: if you really think about it, who actually believes, without doubting the virtue of trying, that with 10,000 hours they could, if not become world champion, then at least reach the top level in their discipline of choice? For anyone who’s hesitating about the answer, here’s another question, which we should all be able to agree on: Who thinks that 10,000 hours of training would give them the courage to walk on a wire 400 meters off the ground? Or, more modestly, just to start small, between the towers of Notre-Dame?