It is probable that the most acceptable theory as to the causes of periodicity is the psychological contention. Human nature is much the same throughout the civilized world. We suffer from a panic and a period of depression, and we grow wary and conservative. This course results in sound methods and accumulation. The business structure rests on a firmer foundation. Gradually the hard lessons of the past are forgotten by the older generation, and are entirely unlearned by the new business generation, all of whom are optimists. Again we expand our enterprises, again fortune favors us; the appetite for gold grows greater as wealth accumulates; men who were economical and satisfied on modest incomes now live extravagantly, and some of them dream of millions. Capital is spread out thinly. Story after story is erected on one foundation, and that foundation, sound enough at first, eventually gives way. Then we must begin our careful building once more. The ten year periods, therefore, may represent with more or less accuracy, the lapse of time between wisdom and folly,--the yard-stick of human intellect and experience. Many of the writers on this subject seem to strive for tangible reasons for each depression. They dive into the subject for a cause and emerge with an effect, or a handful of effects. For example, the depression following 1893 was not caused by the failures of banks and other business institutions, but the failures were caused by the depression. It matters not that the failures ante-dated the bad conditions. Again, the depression itself was produced by prior inflation. It was the illness after over-stimulation. And so, in turn, we can ask what caused the inflation; and the answer is “Human greed and human folly.” This last analysis brings us around in a circle to the original theory of a psychological cause. It is submitted that a dependence on periodicity of any kind, either in the ten year cycles or in year to year events is fraught with danger and cannot be adopted by the speculator. It is chart-playing pure and simple, and the man who disposes of his stocks for no better reason than that a depression appeared ten years ago, is liable to find himself in the position of the chart-enthusiast, who, after tracing a marked uniformity in movements for a period of years, runs into reverses and loses all. It is not meant to say that a knowledge of the past is without value. Inductive reasoning is almost as important as deductive reasoning, when properly employed and applied. If we scrutinize the history of past crises and great movements with a view to determining the salient causes therefor, a great deal has been gained, for we may apply this knowledge to existent elements lying parallel to those which caused trouble in the past, and thus decide what is probable in the future. If, on the other hand, we place dependence on mere repetition, we gain nothing in education and stand in constant danger.