The late Benjamin Graham, Wall Street's high priest of investment philosophy, stately author of four editions of the masterful treatise on investing Security Analysis (McGraw Hill, 1934, 1940, 1951, 1962), was Warren Buffett's professor at Columbia University, his employer at the New York investment firm of Graham-Newman, and his mentor and friend for nearly thirty years. It was Graham who taught Warren that "investment is most intelligent when it is most businesslike." If there is a single credo that Warren holds sacred and to which he attributes his success, it is this concept. It is upon the framework of this single idea that Warren has built his entire financial empire.

Warren's path to riches began in 1957, when friends and family invested $105,000 in his investment limited partnership. Warren's wealth today is valued in excess of $20 billion. Without Graham's tenet of "investing from a business perspective" guiding the way, Warren's performance as an investor might have been no better than the average. With it, he has created one of the great fortunes in contemporary history.

Although Warren readily espouses this philosophy -- be it as the chief executive officer of Berkshire Hathaway, his publicly traded holding company, or in an occasional college lecture -- its subtleties seem to have eluded the investment profession and public up until now. One would think that anyone whose profession is investing would make Warren a serious case study and analyze and dissect his philosophy. But the investment profession and its academic brethren seem to prefer to label him a four-star enigma, and pay essentially only lip service to his real gifts as an investment genius.

What few people realize is that Warren is first and foremost a thinker, a philosopher whose subject matter and realm of expertise are the world of business. He is a man who has taken the investment and business philosophies of some of the greatest minds that have addressed the subjects of commerce and capital and synthesized an absolutely new approach based on these old lessons. His approach is in many ways contrary to conventional Wall Street wisdom.

As we dissect Warren's investment philosophy you will see that he is really

• part Benjamin Graham, from whom he took the concepts of investing from a business perspective and emphasizing price as a major motivating factor in selecting investments
• part Philip Fisher, the legendary California money manager and author, from whom Warren took the idea that the only business worth investing in is one with excellent business economics and the theory that the time to sell an excellent business is never
• part Lawrence N. Bloomberg, 1930s thinker and author, who introduced to both Graham and Warren the idea of the superior investment value of the consumer monopoly (Graham cites Bloomberg in his 1951 edition of Security Analysis)
• part John Burr Williams, 1930s mathematician, financial philosopher, and author of The Theory of Investment Value (Harvard University Press, 1938), from whom Graham acquired the idea that a business's worth is related to what it will earn in the future
• part Lord John Maynard Keynes, famed British economist and author, from whom Warren derived the concept of the concentrated portfolio and the emphasis of learning one area really well and not straying from it
• part Edgar Smith, who in 1924 wrote the then much-heralded, but now long-forgotten Common Stocks As Long-Term Investments (Macmillan, 1924), which introduced to Graham the concept of retained earnings adding value to the business over a period of time
• and most important, part Charlie Munger, legal pundit and financial impresario, who as Warren's friend and partner persuaded him to focus on the more sophisticated philosophy of purchasing excellent businesses at prices that made business sense, instead of seeking only Graham-type bargains.

This is an eclectic group, whose writings span nearly a hundred years of thought on the subject of investing in securities.

Graham was aware of all these philosophies, but it took Warren's extraordinary and unique turn of mind to synthesize them into a strategy that would excel each of their individual efforts. Warren is not afraid of anyone discovering his secret for success, for like any great chef he leaves out a thing or two when discussing the recipes for his best dishes.

Warren is an extremely intelligent and competitive individual. He is not about to give away the store. He has always maintained that great ideas in the realm of investing are few and far between and should be considered proprietary and guarded. He will discuss the details of his philosophy only with members of his family and inner circle. To the rest of the world he feeds tidbits, and then only enough to pique interest. He freely asserts that Graham's Security Analysis is the best book ever written on investing, but he may fail to tell you that Graham's philosophies are not the only ones he embraces today. Graham may have provided the foundation, but he is not the house.

Graham gave Warren the basics, and from there Warren went forward, borrowing and creating as all great geniuses do. But to say that Warren is Graham is to say that Oppenheimer is Einstein, or Balanchine is Diaghilev. One may have been influenced by the other, but in reality they are entirely different beasts.

Warren did not happen into investment genius overnight. His voyage began with Graham's 1934 edition of Security Analysis and has continued through a maze of financial thought to the present. Any strategy used in a highly competitive field requires the ability to adapt and change as the environment evolves. What worked for Graham in the 1930s and 1940s ceased to work for Warren in the 1970s and 1980s.

If one were to compare the relatively pure Grahamian investment style of, say, the legendary portfolio manager/investor Walter Schloss (who studied under and worked for Graham and now runs a very successful investment partnership with his son, in New York City) with Warren's current style, it would be apparent that they are as different as night and day.

Schloss runs an expansive and diversified portfolio, often holding more than a hundred different stocks. He lets price be the dominant force in the reasoning that goes into his buy decision. He searches for stocks selling at a price below their intrinsic value. Schloss, practicing a traditional Grahamian philosophy, then sells any investment that has reached its intrinsic value, thus ending the romance of the economic benefits of a great business and at the same time inviting the tax man to the party.

Warren, on the other hand, runs a far more concentrated portfolio, with the economic nature of the business weighing in just as heavily as price in his determination of what to buy. Warren is also willing to hold a stock forever as long as the economics of the business remain at least the same as when he bought it. This ensures that he will benefit from the compounding effect of retained earnings. It ensures also that he will avoid the profit-eroding taxes that would be imposed if he sold his investment.

Although pure Grahamian philosophy continues to have an exploitable niche in the investment world, its greatest value is as a foundation upon which to learn the investment process. Graham's Security Analysis is more than just a treatise on investing. It is a running historical commentary on the techniques used to evaluate securities for investment purposes. Between 1934 and 1962, Graham wrote four editions of Security Analysis, each deciphering and analyzing old and new methods of security analysis as applied to the present.

One learns through experience, and if not from experience, from those with experience. That is what Graham provides us with. While working for Graham, Warren made a vow that he would not make another investment until he had read Graham's book twelve times. To this day he keeps all four editions next to his desk, and he still finds subtleties that escaped his eye in past readings. As with the Bible, worldly experience enhances each reading of Security Analysis, sparking revelation upon revelation.

Truly, Graham was a man who planted trees so that others could sit underneath them and feast upon their fruit. Thus, it seems only appropriate that we begin your education in Buffettology with the basic tenet of Graham's philosophy and one that Warren holds as the foundation of his own thinking.