A child sitting on books and reading.

Many of the most successful people in history developed voracious reading habits at a young age. Image source: Getty Images.

Napoleon Bonaparte was only 26 years old when he assumed command of the army that defended France's border with Italy. He had never held a position of command before, excepting a handful of small internal skirmishes. Yet in less than a year, against battle-tested Austrian and Hungarian generals with larger armies, Napoleon prevailed in battle after battle and forced his adversaries to sue for peace.

The key to Napoleon's success at such a young age, without experience and up against veteran commanders, was that he had always been a voracious reader. "Much of Napoleon's early childhood [remains] conjectural, but there is little doubt that he was a precocious and prodigious reader, drawn at an early age to history and biography," writes Andrew Roberts in a new biography of the French general.

While his contemporaries played sports outside, Napoleon "would read everything he could about the most ambitious leaders of the ancient world." He studied the rise of the Roman Republic, Hannibal's invasion of it, and the republic's defeat of Carthage. He read Cicero, Voltaire, Diderot, Erasmus, Livy, Virgil, and other philosophers. But his favorite subjects were the conquests of Alexander the Great and Julius Caesar, his heroes. 

Reading about history's greatest military victories and defeats, Napoleon would later tell his junior officers, was the "only way to become a great captain."

Experience by proxy

The central role that reading plays in success comes up time and again in history. It's what enabled a poor orphan who was born to an unwed mother on a small island in the Caribbean to become George Washington's aide-de-camp at age 23. This was the second-most important position in the revolutionary army, and it paved the way for Alexander Hamilton to become one of the nation's founding fathers.

Reading inspired Frederick Douglass to break free from the chains of slavery in 1838. "If you teach [him] how to read, there would be no keeping him," his former master implored upon discovering that his wife was teaching Douglass the alphabet. "From that moment, I understood the pathway from slavery to freedom," Douglass wrote years later in his autobiography. "The very decided manner with which he spoke and strove to impress his wife with the evil consequences of giving me instruction, served to convince me that he was deeply sensible of the truths he was uttering."

More recently, the reading habits of Marine General James Mattis, the newly confirmed secretary of defense, were cited as evidence of his qualifications for the position. "Thanks to my reading, I have never been caught flat-footed by any situation, never at a loss for how any problem has been addressed (successfully or unsuccessfully) before," Mattis wrote in a widely circulated email to a colleague in 2004. "By reading, you learn through others' experiences, generally a better way to do business, especially in our line of work where the consequences of incompetence are so final for young men."

Reading to lead

Reading can play a critical role in one's ascent in any profession, not just the military. For our purposes at The Motley Fool, it's just as crucial if you want to excel as an investor. "I don't think you can get to be a really good investor over a broad range without doing a massive amount of reading," says Charlie Munger. "If [Warren Buffett and I] had been frozen at any given stage, with the knowledge we had, the record would have been much worse than it is. So the game is to keep learning."

Wharton School of Business professor Philip Tetlock makes this same point in Superforecasting, a book about the world's best forecasters. The most important trait of accurate forecasters is "the degree to which one is committed to belief updating and self-improvement," Tetlock writes. "It is roughly three times as powerful a predictor [of one's ability to outperform other forecasters] as its closest rival, intelligence."

But reading just any old book won't do; you have to read to lead. "Reading to lead means pushing yourself -- reading books 'above your level,'" writes Ryan Holiday, a college dropout who became the director of marketing for a publicly traded company at age 21 and a best-selling author by age 24. "You know the books where the words blur together and you can't understand what's happening? Those are the books a leader needs to read. Reading to lead or learn requires that you treat your brain like the muscle that it is -- lifting the subjects with the most tension and weight."

This means reading hard books. "That means pushing ahead into subjects you're not familiar with and wrestling with them until you [are] -- shying away from the 'easy read,'" Holiday continues. "It means reading Feynman over Friedman, biographies over business books, and the classics over the contemporary."

It also relates to the way that one goes about reading. "When I start a book, I almost always go straight to Wikipedia (or Amazon or a friend) and ruin the ending," explains Holiday. "Who cares? Your aim as a reader is to understand WHY something happened, the what is secondary." Read reviews and the forwards to books, which allow one to better deduce the cultural significance of the work. "Read the intro, read all the stuff that comes before the book -- even read the editors notes at the bottom of the pages," says Holiday. "This sets the stage and helps boost your knowledge going into the book."

What this means for investors

For investors, this means reading the classics:

It means reading books by and about the greatest investors:

It means reading books that take effort and attention:

And it means reading books not just to get through them but, more importantly, for the purpose of incorporating their lessons into what Munger refers to as a "latticework of mental models." Be it psychology, history, physics, politics, geography, or anything else, learning about an array of subjects allows you to triangulate ideas, put them into context, and understand their significance more thoroughly.

Reading won't give you all of the answers. It won't turn you into a Buffett or Munger overnight. If that were the case, as Buffett has pointed out, the world's greatest investors would be librarians. What reading will do for you, however, is to give you experience by proxy and, in General Mattis words', "light what is often a dark path ahead."