Security Analysis, authored by professors Benjamin Graham and David Dodd of Columbia University, laid the intellectual foundation for what would later be called "value investing". The work was first published in 1934, following unprecedented losses on Wall Street. In summing up lessons learned, Graham and Dodd chided Wall Street for its myopic focus on a company's reported earnings per share, and were particularly harsh on the favored "earnings trends." They encouraged investors to take an entirely different approach by gauging the rough value of the operating business that lay behind the security. Graham and Dodd enumerated multiple actual examples of the market's tendency to irrationally under-value certain out-of-favor securities. They saw this tendency as an opportunity for the savvy.
At bottom, Security Analysis stands for the proposition that a well-disciplined investor can determine a rough value for a company from all of its financial statements, make purchases when the market inevitably under-prices some of them, earn a satisfactory return, and never be in real danger of permanent loss. Warren Buffett, the only student in Graham's investment seminar to earn an A+, made billions of dollars by methodically and rationally implementing the tenets of Graham and Dodd's book.