The graph does show one tremendous rise and collapse which stands out starkly from all the other fluctuations. This is commonly called the "new era" stock market of 1927-33. The striking feature of this phenomenon was that the new era existed solely in the minds of market speculators. The whole episode, in retrospect, now seems to have been one of those rare manifestations of mass financial madness which we used to study in our history books under the titles of "the South Sea Bubble", "the Mississippi Bubble" and so on.

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