"In 1924, Edgar Lawrence Smith, an obscure economist and financial advisor, wrote Common Stocks as Long Term Investments, a slim book that changed the investment world. Indeed, writing the book changed Smith himself, forcing him to reassess his own investment beliefs. Going in, he planned to argue that stocks would perform better than bonds during inflationary periods and that bonds would deliver superior returns during deflationary times. That seemed sensible enough. But Smith was in for a shock. His book began, therefore, with a confession: “These studies are the record of a failure – the failure of facts to sustain a preconceived theory.” Luckily for investors, that failure led Smith to think more deeply about how stocks should be evaluated. For the crux of Smith’s insight, I will quote an early reviewer of his book, none other than John Maynard Keynes: “I have kept until last what is perhaps Mr. Smith’s most important, and is certainly his most novel, point. Well-managed industrial companies do not, as a rule, distribute to the shareholders the whole of their earned profits. In good years, if not in all years, they retain a part of their profits and put them back into the business. Thus there is an element of compound interest (Keynes’ italics) operating in favour of a sound industrial investment. Over a period of years, the real value of the property of a sound industrial is increasing at compound interest, quite apart from the dividends paid out to the shareholders.” And with that sprinkling of holy water, Smith was no longer obscure."