* The answer is that a round manhole cover can't fall into the manhole, no matter how much you twist and turn it. A rectangular cover can: All you have to do is tilt it sideways. There: now you can get a job at Microsoft.

* The "IQ fundamentalist" Arthur Jensen put it thusly in his 1980 book Bias in Mental Testing (p. 113): "The four socially and personally most important threshold regions on the IQ scale are those that differentiate with high probability between persons who, because of their level of general mental ability, can or cannot attend a regular school (about IQ 50), can or cannot master the traditional subject matter of elementary school (about IQ 75), can or cannot succeed in the academic or college preparatory curriculum through high school (about IQ 105), can or cannot graduate from an accredited four-year college with grades that would qualify for admission to a professional or graduate school (about IQ 115). Beyond this, the IQ level becomes relatively unimportant in terms of ordinary occupational aspirations and criteria of success. That is not to say that there are not real differences between the intellectual capabilities represented by IQs of 115 and 150 or even between IQs of 150 and 180. But IQ differences in this upper part of the scale have far less personal implications than the thresholds just described and are generally of lesser importance for success in the popular sense than are certain traits of personality and character."

* Just to be clear: it is still the case that Harvard produces more Nobel Prize winners than any other school. Just look at those lists. Harvard appears on both of them, a total of three times. A school like Holy Cross appears just once. But wouldn't you expect schools like Harvard to win more Nobels than they do? Harvard is, after all, the richest, most prestigious school in history and has its pick of the most brilliant undergraduates the world over.

* To get a sense of how absurd the selection process at elite Ivy League schools has become, consider the following statistics. In 2008, 27,462 of the most highly qualified high school seniors in the world applied to Harvard University. Of these students, 2,500 of them scored a perfect 800 on the SAT critical reading test and 3,300 had a perfect score on the SAT math exam. More than 3,300 were ranked first in their high school class. How many did Harvard accept? About 1,600, which is to say they rejected 93 out of every 100 applicants. Is it really possible to say that one student is Harvard material and another isn't, when both have identical-and perfect-academic records? Of course not. Harvard is being dishonest. Schwartz is right. They should just have a lottery.

* Here's another student's answers. These might be even better than Poole's: "(Brick). To break windows for robbery, to determine depth of wells, to use as ammunition, as pendulum, to practice carving, wall building, to demonstrate Archimedes' Principle, as part of abstract sculpture, cosh, ballast, weight for dropping things in river, etc., as a hammer, keep door open, footwiper, use as rubble for path filling, chock, weight on scale, to prop up wobbly table, paperweight, as firehearth, to block up rabbit hole."

* Most estimates put the heritability of IQ at roughly 50 percent.

* The lawyer and novelist Louis Auchincloss, who very much belongs to the old WASP-y white-shoe legal establishment in New York, has a scene in his book The Scarlet Letters that perfectly captures the antipathy the downtown firms felt toward takeover law. "Face it, my dear, your husband and I are running a firm of shysters," a takeover attorney explains to the wife of his law partner.

He continues: "Nowadays when one wishes to acquire a company that doesn't wish to be acquired, one's counsel bring all kinds of nuisance suits to induce it to change its mind. We sue for mismanagement by the directors, for unpaid dividends, for violation of the bylaws, for improper issuance of stock. We allege criminal misconduct; we shout about antitrust; we sue for ancient and dubious liabilities. And our opponent's counsel will answer with inordinate demands for all our files and seek endless interrogatories in order to enmesh our client in a hopeless tangle of red tape.... It is simply war, and you know the quality that applies to that and love."

* The best analysis of how adversity turned into opportunity for Jewish lawyers has been done by the legal scholar Eli Wald. Wald is careful to make the point, however, that Flom and his ilk weren't merely lucky. Lucky is winning the lottery. They were given an opportunity, and they seized it. As Wald says: "Jewish lawyers were lucky and they helped themselves. That's the best way to put it. They took advantage of the circumstances that came their way. The lucky part was the unwillingness of the WASP firms to step into takeover law. But that word luck fails to capture the work and the efforts and the imagination and the acting on opportunities that might have been hidden and not so obvious."

* Janklow and Nesbit, the agency he started, is, in fact, my literary agency. That is how I heard about Janklow's family history.

* I realize that it seems strange to refer to American Jewish immigrants as lucky when the families and relatives they left behind in Europe were on the verge of extermination at the hands of the Nazis. Borgenicht, in fact, unwittingly captures this poignancy in his memoir, which was published in 1942. He called it The Happiest Man. After numerous chapters brimming with optimism and cheer, the book ends with the sobering reality of Nazi-dominated Europe. Had The Happiest Man been published in 1945, when the full story of the Holocaust was known, one imagines it would have had a very different title.

* Just to be clear: to say that garment work was meaningful is not to romanticize it. It was incredibly hard and often miserable labor. The conditions were inhuman. One survey in the 1890s put the average workweek at eighty-four hours, which comes to twelve hours a day. At times, it was higher. "During the busy season," David Von Drehle writes in Triangle: The Fire That Changed Amierca, "it was not unusual to find workers on stools or broken chairs, bent over their sewing or hot irons, from 5 a.m. to 9 p.m., a hundred or more hours a week. Indeed, it was said that during the busy seasons the grinding hum of sewing machines never entirely ceased on the Lower East Side, day or night."

* The conventional explanation for Jewish success, of course, is that Jews come from a literate, intellectual culture. They are famously "the people of the book." There is surely something to that. But it wasn't just the children of rabbis who went to law school. It was the children of garment workers. And their critical advantage in climbing the professional ladder wasn't the intellectual rigor you get from studying the Talmud. It was the practical intelligence and savvy you get from watching your father sell aprons on Hester Street.

* David Hackett Fischer's book Albion's Seed: Four British Folkways in America is the most definitive and convincing treatment of the idea that cultural legacies cast a long historical shadow. (If you read my first book, The Tipping Point, you'll remember that the discussion of Paul Revere was drawn from Fischer's Paul Revere's Ride.) In Albion's Seed, Fischer argues that there were four distinct British migrations to America in its first 150 years: first the Puritans, in the 1630s, who came from East Anglia to Massachusetts; then the Cavaliers and servants, who came from southern England to Virginia in the mid-seventeenth century; then the Quakers, from the North Midlands to the Delaware Valley between the late seventeenth and early eighteenth centuries; and finally, the people of the borderlands to the Appalachian interior in the eighteenth century. Fischer argues brilliantly that those four cultures-each profoundly different-characterize those four regions of the United States even to this day.

* Cohen has done other experiments looking again for evidence of "southernness," and each time he finds the same thing. "Once, we bothered students with persistent annoyances," he said. "They come into the lab and they are supposed to draw pictures from their childhood. They are doing this with the confederate, and he's being a jerk. He does all these things to persistently annoy the subject. He'll wad up his drawing and throw it at the wastebasket and hit the subject. He'll steal the subject's crayons and not give them back. He keeps on calling the subject 'Slick,' and he says, 'I'm going to put your name on your drawing,' and writes 'Slick.' What you find is that northerners tend to give off displays of anger, up to a certain point, at which point they level off. Southerners are much less likely to be angry early on. But at some point they catch up to the northerners and shoot past them. They are more likely to explode, much more volatile, much more explosive."

* How are these kinds of attitudes passed down from generation to generation? Through social heritance. Think of the way accents persist over time. David Hackett Fischer points out that the original settlers of Appalachia said: "whar for where, thar for there, hard for hired, critter for creature, sartin for certain, a-goin for going, hit for it, he-it for hit, far for fire, deef for deaf, pizen for poison, nekkid for naked, eetch for itch, boosh for bush, wrassle for wrestle, chaw for chew, poosh for push, shet for shut, ba-it for bat, be-it for be, narrer for narrow, winder for window, widder for widow, and young-uns for young one." Recognize that? It's the same way many rural people in the Appalachians speak today. Whatever mechanism passes on speech patterns probably passes on behavioral and emotional patterns as well.

* Korean Air was called Korean Airlines before it changed its name after the Guam accident. And the Barents Sea incident was actually preceded by two other crashes, in 1971 and 1976.

* This is true not just of plane crashes. It's true of virtually all industrial accidents. One of the most famous accidents in history, for example, was the near meltdown at Pennsylvania's Three Mile Island nuclear station in 1979. Three Mile Island so traumatized the American public that it sent the US nuclear power industry into a tailspin from which it has never fully recovered. But what actually happened at that nuclear reactor began as something far from dramatic. As the sociologist Charles Perrow shows in his classic Normal Accidents, there was a relatively routine blockage in what is called the plant's "polisher"-a kind of giant water filter. The blockage caused moisture to leak into the plant's air system, inadvertently tripping two valves and shutting down the flow of cold water into the plant's steam generator. Like all nuclear reactors, Three Mile Island had a backup cooling system for precisely this situation. But on that particular day, for reasons that no one really understands, the valves for the backup system weren't open. Someone had closed them, and an indicator in the control room showing they were closed was blocked by a repair tag hanging from a switch above it. That left the reactor dependent on another backup system, a special sort of relief valve. But, as luck would have it, the relief valve wasn't working properly that day either. It stuck open when it was supposed to close, and, to make matters even worse, a gauge in the control room that should have told the operators that the relief valve wasn't working was itself not working. By the time Three Mile Island's engineers realized what was happening, the reactor had come dangerously close to a meltdown.

No single big thing went wrong at Three Mile Island. Rather, five completely unrelated events occurred in sequence, each of which, had it happened in isolation, would have caused no more than a hiccup in the plant's ordinary operation.

* We know this because the flight attendant survived the crash and testified at the inquest.

* Hofstede, similarly, references a study done a few years ago that compared German and French manufacturing plants that were in the same industry and were roughly the same size. The French plants had, on average, 26 percent of their employees in management and specialist positions; the Germans, 16 percent. The French, furthermore, paid their top management substantially more than the Germans did. What we are seeing in that comparison, Hofstede argued, is a difference in cultural attitudes toward hierarchy. The French have a power distance index twice that of the Germans. They require and support hierarchy in a way the Germans simply don't.

* Here are the top five pilot PDIs by country. If you compare this list to the ranking of plane crashes by country, they match up very closely.

1. Brazil

2. South Korea

3. Morocco

4. Mexico

5. Philippines

The five lowest pilot PDIs by country are:

15. United States

16. Ireland

17. South Africa

18. Australia

19. New Zealand

* On international comparison tests, students from Japan, South Korea, Hong Kong, Singapore, and Taiwan all score roughly the same in math, around the ninety-eighth percentile. The United States, France, England, Germany, and the other Western industrialized nations cluster at somewhere between the twenty-six and thirty-sixth percentile. That's a big difference.

Lynn's claim that Asians have higher IQs has been refuted, convincingly, by a number of other experts, who showed that he based his argument on IQ samples drawn disproportionately from urban, upper-income homes. James Flynn, perhaps the world's leading expert on IQ, has subsequently made a fascinating counterclaim. Asians' IQs, he says, have historically been slightly lower than whites' IQs, meaning that their dominance in math has been in spite of their IQ, not because of it. Flynn's argument was outlined in his book Asian Americans: Achievement Beyond IQ (1991).

* Two small points. Mainland China isn't on this list because China doesn't yet take part in the TIMSS study. But the fact that Taiwan and Hong Kong rank so highly suggests that the mainland would probably also do really well.

Second, and perhaps more important, what happens in the north of China, which isn't a wet-rice agriculture society but historically a wheat-growing culture, much like Western Europe? Are they good at math too? The short answer is that we don't know. The psychologist James Flynn points out, though, that the overwhelming majority of Chinese immigrants to the West-the people who have done so well in math here-are from South China. The Chinese students graduating at the top of their class at MIT are the descendants, chiefly, of people from the Pearl River Delta. He also points out that the lowest-achieving Chinese Americans are the so-called Sze Yap people, who come from the edges of the Delta, "where soil was less fertile and agriculture less intense."

There is actually a significant scientific literature measuring Asian "persistence." In a typical study, Priscilla Blinco gave large groups of Japanese and American first graders a very difficult puzzle and measured how long they worked at it before they gave up. The American children lasted, on average, 9.47 minutes. The Japanese children lasted 13.93 minutes, roughly 40 percent longer.

* KIPP stands for "Knowledge Is Power Program."