Pilgrim Fathers in New England, William Penn in Pennsylvania, Lord Baltimore in Maryland aimed to organize local intentional communities. Similar efforts were made by the Mennonites, the Dukhobors, the Hutterites, the Mormons in North America. The Christians during the decline of Roman civilization led a movement to convert a large geographical area to a new and better way of life. Followers of Mohammed, several centuries later, made a similar effort to convert the Eurasian-African world to their ways of thinking and acting. Young people by the thousands, in the United States and other western countries, are turning their backs on western civilization and are organizing enlarged families and communes that provide their members with a modified social order which aims at improvements here and now. Necessarily such social experiments are looked upon with suspicion by the Establishment. They are "new", "different", "subversive", "godless", "wicked." Hence, they are criticized, denounced, raided and often broken up as threats to existing law and order. Intentional communities may grow out of consumers' cooperation. They may begin as farm collectives. Generally, however, they consist of the followers of outstanding leaders of religious or ethical sects. Many intentional communes spring up, mushroom-fashion, and disappear with equal rapidity. Others endure for generations and centuries. In a very real sense they are pilot plants designed to correct individual or social maladjustments and substitute new ways for old ones. As pilot plants they experiment with deviations from existing social norms, acting as a social laboratory in which new ideas and practices are tested, modified, accepted, rejected. Change is one of the essential aspects of every society. There are changes in personnel. In each generation individuals grow old and retire. Others grow up and take over the tasks of organizing the communities in which they live. Profound social changes result from discoveries and inventions: the wheel, the arch, steam and gas engines, electricity, atomic power. Cyclic changes occur in the economy. Social changes follow alterations in the weather. Nations, empires, civilizations are produced by the changing life forms. During long periods, social changes are so gradual that they are unnoticed save by the more sensitive and perceptive. At other times, social changes tumble over one another in an overwhelming revolutionary flood which sweeps away the old, yielding place to new, "lest one good custom should corrupt the world". Changes in society beget changes in ideology. Reciprocally, changes in ideology lead to changes in social structure and function. The more rigid the social order, the more stubborn its resistance to change. By the same token, more fluid societies lend themselves more readily to changes in practice and in theory.