Answering with some decency the first two questions asked by Prabhu Guptara would alone require an articulate history of business cycle and crises theories: a bit too much for a post to this list. Nevertheless, a sketchy attempt can be done. 1) The statistical understanding of business cycles. Most of the authors writing on business cycles since the 1890s up to the 1920s had an historical or statistical section in their books. The statistical methods were more or less refined, but it is worth noting that often titles themselves of the books referred to the history of crises/cycles. Just think of Tugan Baranowsky, Spiethoff, Aftalion, Bouniatian, Robertson, Pigou, Hawtrey, Mitchell (1913). The first full-blown attempt at elaborating business cycle statistics was probably Juglar in 1862 (preceded by some statistical articles in the late 1850s), followed by Jevons. Histories of crises (in the plural) were already published in the 1850s. 2) The second question, "whoever did the first identification, and whenever that was, when exactly did business cycles first start affecting industrial society?" simply cannot be answered as it is formulated, due to the changing nature of the "cycle" itself, and of the economists' (or writers on the subject: which in the XIX century was certainly not the same thing) ways of understanding what crises/cycles are. Some periodicity in the recurring of crises was noted (some say it was common place) by the end of the 1820s. By the early 1830s we have the first attempts to explain endogenously (or semi-endogenously) the recurrence of these events: mostly in terms of the repetition of crises (with emphasis on the most dramatic part of the cycle), occasionally directly in terms of cycles. The family of explanations in terms of recurring crises gave way to purely cyclical explanation just before WWI. A passage by Mitchell (a rethorical masterpiece) records the change of the intellectual climate: "Wide divergences of opinion continue to exist among competent writers upon crises; but in recent years substantial agreement has been reached upon two points of fundamental importance. Crises are no longer treated as sudden catastrophes which interrupt the ?normal? course of business, as episodes which can be understood without investigation of the intervening years. On the contrary, the crisis is regarded as but the most dramatic and briefest of the three phases of a business cycle ?prosperity, crisis, and depression. Modern discussion endeavor to show why a crisis is followed by a depression, and depression by prosperity, quite as much as to show why prosperity is followed by a crisis. In a word, the theory of crises has grown into the theory of business cycles. The wider grasp of the problem has discredited the view that crises are due to abnormal conditions which tempt industry and trade to forsake their beaten paths and temporarily befog the judgement of business men and investors, or to misguided legislation, unsound business practices, imperfect banking organization, and the like. As business cycles have continued to run their round decade after decade in all nations of highly developed business organization, the idea that each crisis may be accounted for by some special cause has become less tenable. On the contrary, the explanations in favor today ascribe the recurrence of crises after periods of prosperity to some inherent characteristic of economic organization or activity. The complex processes which make up business life are analyzed to discover why they inevitably work out a change from good times to bad and from bad times to good. The influence of special conditions is admitted, of course, but rather as a factor which complicates the process than as the leading cause of crises" (Mitchell 1913, pp. 5?6). Back to the question. When cycles started to effect industrial societies depends on what one means by 'cycles'. If we take Mitchell seriously, that the phenomenon he and his contemporaries were classifying as 'cycles' was the same phenomenon earlier writers called 'crises', or recurring crises, then one can say that crises affected industrial societies at least early enough to permit to people at the end of the 1820s to recognise such events as somehow periodical. The literature records ample discussions (professional, and in the press and by means of pamphlets, financial journals, etc.) after each crisis, emphasising the distress caused by each of these events. So that story goes back at least 180 years. Daniele Besomi