Over the past eight years I set out to write about 10 people who, by almost any measure, actually did change the world. Their achievements had to be so spectacular that they not only changed their world, but that the impact of what they did extended to our era, as well. The characters couldn’t be just great thinkers but instead they had to be doers — people who ushered in a whole new age by rolling up their sleeves and driving civilization to a higher plane.

When I began my research into the lives and times of these 10 path breakers, I had no idea what they would have in common, if anything. After all, they lived in different eras and their achievements were in vastly different fields. It was only after I researched and wrote about them that I sat back and asked, “What observations could I make about the ten as a group? How did they achieve what they did?”

I drew three major conclusions.

First, all my protagonists were, in the famous words of philosopher Isaiah Berlin, “hedgehogs” and not “foxes.” Hedgehogs know and do one big thing. They are pathologically relentless in pursuit of a single, big idea. Foxes pursue multiple projects but in a shallower way. A good example of the former is Jean Monnet. From his early twenties during World War I, he was obsessed with closer relations among European nations, and he pressed for that until well after he had created the European Coal and Steel Community in 1951, the forerunner of the European Union. Likewise, Cyrus Field oversaw the building of the transatlantic telegraph, possibly the most important global communications project in history, over a period of some two decades during which he did nothing else but try and fail, over and over, until he got it all right.

Second, as far reaching as their achievements were, none of my characters bent the river of history. Instead, they just quickened the currents. They succeeded because historical circumstances gave them the opening, and because they seized the opportunity quicker and better than others who might well have done the same thing. In other words, they needed exceptional preconditions to rise to truly heroic levels. A case in point was Margaret Thatcher in the 1980s. Yes, she was a highly skilled politician who could make a crystal clear case for radical change in the form of replacing socialism with laissez faire policies. But the great winds in her sails came from the utter policy failure of Great Britain for the previous decade, a near collapse of the economy and a breakdown in effective governance that made the population demand and accept radical change. I could make a similar argument with Chinese premiere Deng Xiaoping, who opened China to the world after Mao’s three decades of having sealed itself off, and whose great advantage was that his predecessor’s policies were an abject failure, forcing China to miss out on all the progress that was happening in East Asia and created misery for hundreds of millions of its citizens.

Third, while each of my protagonists was responsible for a huge advance in bringing heretofore disconnected societies closer together, that wasn’t their goal. They didn’t care a wit about globalization. They were preoccupied with something else –personal power, amassing wealth, insuring their own stature — and they were all riveted on a set of problems before them that they had to solve. In the fifteenth century, Prince Henry built the ships, organized the crews, and brought to bear the latest nautical techniques, allowing Portuguese and other European explorers to eventually reach Asia as well as the Americas. In the process he became the father of European seaborne exploration. While Henry said his principal aim was spreading Christianity around the world, as the third son of an impoverished king his bigger purpose was generating an income and a reputation that he could achieve by no other means. Mayer Amschel Rothschild climbed out of Europe’s most oppressive Jewish ghetto in the late eighteenth century to build, together with his five sons, the most powerful private bank the world had seen and virtually create the global bond market. Nevertheless, I doubt they gave a thought to building a more peaceful, integrated world. They just wanted to get rich.

So one moral of the story is this: If you are searching for men and woman who will really change the world , beware of those whose efforts, no matter how monumental, are too scattered. Look askance at those who claim they are creating history rather than taking advantage of its ebb and flow. And be suspicious of those who, even with the utmost of sincerity, profess excessive idealism. Such people may well do wonderful things, but they are likely to fall short of real transformational leadership.

Jeffrey E. Garten is dean emeritus of the Yale School of Management and author of From Silk to Silicon: The Story of Globalization Through Ten Extraordinary Lives ( forthcoming March 1).