56 John Kluge 40.0 Germany Metropolitan Broadcasting Company

57 J. P. Morgan 39.8 United States General Electric, US Steel

58 Oliver H. Payne 38.8 United States Standard Oil Company

59 Yoshiaki Tsutsumi 38.1 Japan Seibu Corporation

60 Henry Clay Frick 37.7 United States Carnegie Steel Company

61 John Jacob Astor IV 37.0 United States Inheritance

62 George Pullman 35.6 United States Pullman Company

63 Collis Potter Huntington 34.6 United States Central Pacific Railroad

64 Peter Arrell Brown Widener 33.4 United States American Tobacco Company

65 Philip Danforth Armour 33.4 United States Armour Refrigerator Line

66 William S. O'Brien 33.3 United States Consolidated Virginia Mining Company

67 Ingvar Kamprad 33.0 Sweden IKEA

68 K. P. Singh 32.9 India DLF Universal Limited

69 James C. Flood 32.5 United States Consolidated Virginia Mining Company

70 Li Ka-shing 32.0 China Hutchison Whampoa Limited

71 Anthony N. Brady 31.7 United States Brooklyn Rapid Transit

72 Elias Hasket Derby 31.4 United States Shipping

73 Mark Hopkins 30.9 United States Central Pacific Railroad

74 Edward Clark 30.2 United States Singer Sewing Machine

75 Prince Al-Waleed bin Talal 29.5 Saudi Arabia Kingdom Holding Company

Do you know what's interesting about that list? Of the seventy-five names, an astonishing fourteen are Americans born within nine years of one another in the mid-nineteenth century. Think about that for a moment. Historians start with Cleopatra and the pharaohs and comb through every year in human history ever since, looking in every corner of the world for evidence of extraordinary wealth, and almost 20 percent of the names they end up with come from a single generation in a single country.

Here's the list of those Americans and their birth years:

1. John D. Rockefeller, 1839

2. Andrew Carnegie, 1835

28. Frederick Weyerhaeuser, 1834

33. Jay Gould, 1836

34. Marshall Field, 1834

35. George F. Baker, 1840

36. Hetty Green, 1834

44. James G. Fair, 1831

54. Henry H. Rogers, 1840

57. J. P. Morgan, 1837

58. Oliver H. Payne, 1839

62. George Pullman, 1831

64. Peter Arrell Brown Widener, 1834

65. Philip Danforth Armour, 1832

What's going on here? The answer becomes obvious if you think about it. In the 1860s and 1870s, the American economy went through perhaps the greatest transformation in its history. This was when the railroads were being built and when Wall Street emerged. It was when industrial manufacturing started in earnest. It was when all the rules by which the traditional economy had functioned were broken and remade. What this list says is that it really matters how old you were when that transformation happened.

If you were born in the late 1840s you missed it. You were too young to take advantage of that moment. If you were born in the 1820s you were too old: your mind-set was shaped by the preCivil War paradigm. But there was a particular, narrow nine-year window that was just perfect for seeing the potential that the future held. All of the fourteen men and women on the list above had vision and talent. But they also were given an extraordinary opportunity, in the same way that hockey and soccer players born in January, February, and March are given an extraordinary opportunity.*

Now let's do the same kind of analysis for people like Bill Joy and Bill Gates.

If you talk to veterans of Silicon Valley, they'll tell you that the most important date in the history of the personal computer revolution was January 1975. That was when the magazine Popular Electronics ran a cover story on an extraordinary machine called the Altair 8800. The Altair cost $397. It was a do-it-yourself contraption that you could assemble at home. The headline on the story read: "PROJECT BREAKTHROUGH! World's First Minicomputer Kit to Rival Commercial Models."

To the readers of Popular Electronics, in those days the bible of the fledgling software and computer world, that headline was a revelation. Computers up to that point had been the massive, expensive mainframes of the sort sitting in the white expanse of the Michigan Computer Center. For years, every hacker and electronics whiz had dreamt of the day when a computer would come along that was small and inexpensive enough for an ordinary person to use and own. That day had finally arrived.

If January 1975 was the dawn of the personal computer age, then who would be in the best position to take advantage of it? The same principles apply here that applied to the era of John Rockefeller and Andrew Carnegie.

"If you're too old in nineteen seventy-five, then you'd already have a job at IBM out of college, and once people started at IBM, they had a real hard time making the transition to the new world," says Nathan Myhrvold, who was a top executive at Microsoft for many years. "You had this multibillion-dollar company making mainframes, and if you were part of that, you'd think, Why screw around with these little pathetic computers? That was the computer industry to those people, and it had nothing to do with this new revolution. They were blinded by that being the only vision of computing. They made a nice living. It's just that there was no opportunity to become a zillionaire and make an impact on the world."

If you were more than a few years out of college in 1975, then you belonged to the old paradigm. You had just bought a house. You're married. A baby is on the way. You're in no position to give up a good job and pension for some pie-in-the-sky $397 computer kit. So let's rule out all those born before, say, 1952.

At the same time, though, you don't want to be too young. You really want to get in on the ground floor, right in 1975, and you can't do that if you're still in high school. So let's also rule out anyone born after, say, 1958. The perfect age to be in 1975, in other words, is old enough to be a part of the coming revolution but not so old that you missed it. Ideally, you want to be twenty or twenty-one, which is to say, born in 1954 or 1955.

There is an easy way to test this theory. When was Bill Gates born?

Bill Gates: October 28, 1955