The underlying principle in “The Intelligent Investor,” first published in 1949, was that an intelligent investor considering an investment in a company’s stock should analyze the value of that company’s business and compare it to the stock price. Back in 1949, many so-called investors bought and sold stocks while having little or no understanding of their underlying values, presenting a significant edge to investors who actually did analyze companies. Charles Brandes learned this principle directly from Graham before starting his firm in 1974. Fifty years later, we continue to observe that many so-called investors still buy and sell with little or no understanding of underlying value. 

Source: The Intelligent Investor: A Book of Practical Counsel—Revised Edition, Benjamin Graham. Updated with New Commentary by Jason Zweig (HarperCollins, 1973, 2003)