Ben Graham had become well known during the 1920's. At a time when the rest of the world was approaching the investment arena as a giant game of roulette, he searched for stocks that were so inexpensive they were almost completely devoid of risk. One of his best known calls was the Northern Pipe Line, an oil transportation company managed by the Rockefellers. The stock was trading at $65 a share, but after studying the balance sheet, Graham realized that the company had bond holdings worth $95 for every share. The value investor tried to convince management to sell the portfolio, but they refused. Shortly thereafter, he waged a proxy war and secured a spot on the Board of Directors. The company sold its bonds and paid a dividend in the amount of $70 per share.
When he was 40 years old, Ben Graham published Security Analysis, one of the greatest works ever penned on the stock market. At the time, it was risky; investing in equities had become a joke (the Dow Jones had fallen from 381.17 to 41.22 over the course of three to four short years following the crash of 1929). It was around this time that Graham came up with the principle of "intrinsic" business value - a measure of a business's true worth that was completely and totally independent of the stock price. Using intrinsic value, investors could decide what a company was worth and make investment decisions accordingly. His subsequent book, The Intelligent Investor, which Warren celebrates as "the greatest book on investing ever written", introduced the world to Mr. Market - the best investment analogy in history.
Through his simple yet profound investment principles, Ben Graham became an idyllic figure to the twenty-one year old Warren Buffett. Reading an old edition of Who's Who, Warren discovered his mentor was the Chairman of a small, unknown insurance company named GEICO. He hopped a train to Washington D.C. one Saturday morning to find the headquarters. When he got there, the doors were locked. Not to be stopped, Buffett relentlessly pounded on the door until a janitor came to open it for him. He asked if there was anyone in the building. As luck (or fate) would have it, there was. It turns out that there was a man still working on the sixth floor. Warren was escorted up to meet him and immediately began asking him questions about the company and its business practices; a conversation that stretched on for four hours. The man was none other than Lorimer Davidson, the Financial Vice President. The experience would be something that stayed with Buffett for the rest of his life. He eventually acquired the entire GEICO company through his corporation, Berkshire Hathaway.
Flying through his graduate studies at Columbia, Warren Buffett was the only student ever to earn an A+ in one of Graham's classes. Disappointingly. both Ben Graham and Warren's father advised him not to work on Wall Street after he graduated. Absolutely determined, Buffett offered to work for the Graham partnership for free. Ben turned him down. He preferred to hold his spots for Jews who were not hired at Gentile firms at the time. Warren was crushed.
Returning home, he took a job at his father's brokerage house and began seeing a girl by the name of Susie Thompson. The relationship eventually turned serious and in April of 1952 the two were married. They rented out a three-room apartment for $65 a month; it was run-down and served as home to several mice. It was here their daughter, also named Susie, was born. In order to save money, they made a bed for her in a dresser drawer.
During these initial years, Warren's investments were predominately limited to a Texaco station and some real estate, but neither were successful. It was also during this time he began teaching night classes at the University of Omaha (something that wouldn't have been possible several months before. In an effort to conquer his intense fear of public speaking, Warren took a course by Dale Carnegie). Thankfully, things changed. Ben Graham called one day, inviting the young stockbroker to come to work for him. Warren was finally given the opportunity he had long awaited.
source: about.com