Past experience appears to have particular validity and value in dealing with the stock market. The good old rules all seem to be good still. It is conceivable, of course, that the continuity of the market may end someday—perhaps tomorrow—and past experience may really prove an handicap in meeting the new conditions, as it appeared to be a handicap for a great many months in 1927-29. But is it not the part of intelligence to run the small risk of being wrong by sticking to the old principles, rather than to run the big risk of being wrong by breaking away from past experience?

Chapter II, The Investor and Stock-Market Fluctuations, p. 36 - The Intelligent Investor: The Classic Text on Value Investing (1949)