Many people consider Berkshire Hathaway (NYSE:BRK.A) Chairman Warren Buffett to be America's greatest investor. But whom might you find on Warren's own pedestal? A guy named Benjamin Graham, under whose tutelage Warren worked many moons ago.

Although Graham's record doesn't beat Buffett's, he was no slouch. Between 1929 and 1956, a period spanning the Great Depression and several major wars, Graham's investments grew an average of about 17% per year.

Ben Graham is known as the father of value investing. Value, or "defensive," investors quietly seek out bargains among underpriced companies, buy into them, and then patiently wait for their fair value to be realized. Growth investors, on the other hand, are more aggressive. They aim to buy businesses that are booming, often due to high demand for their products. While growth investors will buy a dollar hoping for it to become two dollars, value investors will try to buy a dollar for 50 cents. Both approaches have their merits, and Warren Buffett's approach combines the two.

Graham was a pioneer in emphasizing the importance of crunching numbers. After experiencing the devastation of the 1929 crash, he sought to develop resilient techniques that could be used by any investor. He popularized examining price-to-earnings (P/E) ratios, debt-to-equity ratios, dividend records, net current assets, book values, and earnings growth. (Thanks, Ben!) Graham knew what he was looking for and demanded high quality on every count.

Graham's focus was on objective numbers rather than more subjective aspects such as management, trends, brand names, and new products. The data he tapped was publicly available, via corporate financial statements and the Standard & Poor's Stock Guide (available for free from many brokerages).

In 1934, Graham co-authored with David Dodd a hefty textbook called Security Analysis. Nearly seven decades later, it's still widely used in business schools. As it's not the easiest read, we recommend his more concise work, The Intelligent Investor. Warren Buffett himself has referred to The Intelligent Investor as "by far the best book about investing ever written." Pick up a copy at your local library and check it out.

Learn more about Benjamin Graham in this Richard Rockwood article and in this Tom Jacobs article on investing like Benjamin Graham.