[13] To this cause of immobility may be added others, such as: (1) Narrow experience and few interests. (2) Large percentage of population owning property. (3) Oriental pride in permanence. (4) Fatalistic philosophies. (5) Over-emphasis of government. [14] Thomas, _op. cit._, pp. 20, 21. Social changes follow both minor and major disasters. The destruction of a mill may change the economic outlook of a village. The loss of a bridge may result in an entirely different school system for an isolated community; a cloud-burst may move a town. Great visitations, like the Chicago fire or the San Francisco earthquake, reveal these social processes in larger and more legible scale. Take as a single instance the latter city. Its quick recovery has been called one of the wonders of the age. In the very midst of surrounding desolation and business extinction, the Californian city projected a Panama-Pacific exposition, and its citizens proceeded to arrange for one of the greatest of all world fairs. On the other hand, the social changes which succeed relatively small disturbances are often such as to elude an estimate. The reason has been well suggested that "big crises bring changes about most easily because they affect all individuals alike at the same time." In other words a more general fluidity is accomplished. We see, therefore, a second principle begin to emerge. Not only is fluidity fundamental to social change, but the degree of fluidity seems to vary directly as the shock and extent of the catastrophe. There yet remains to notice the bearing of catastrophe upon social progress. The following words are quotable in this connection: It is quite certain that the degree of progress of a people has a certain relation to the number of disturbances encountered, and the most progressive have had a more vicissitudinous life. Our proverb "Necessity is the mother of invention" is the formulation in folk-thought of this principle of social change.[15]