It is surprising to many to discover that the "Pennsylvania Dutch" were part of the same movement of population which brought the Quakers into Pennsylvania. William Penn spoke German as well as English. His mother was a German. When he inherited his father's claim against the British Crown, and received from Charles the Second the grant of that extensive territory in America on which he launched his Holy Experiment, he began to advertise and to seek for settlers on the Continent as well as in England. William Penn was a Quaker, and on the Continent he found immediate response in the greatest number of cases among the various branches of Mennonites, Anabaptist, and other sects, who shared a common group of beliefs and experienced at this time a common persecution. William Penn, therefore, reaped a harvest of responses in the territory between the mouth of the Rhine and the Alps. His proposal made its own selection, and brought to America a population calculated like the Quaker population for the building of communities. The largest single contribution was made by the Palatinates, who were at that period undergoing extreme persecution. The communities founded within the first century after the opening of Pennsylvania have remained to the present day, and the earliest establishments of Mennonites and Quaker communities in Pennsylvania have been duplicated in the westward stream of immigration, especially in Ohio and in Iowa. These people are roughly called the "Pennsylvania Dutch." Even when one meets them in Michigan, Iowa or Minnesota, this name clings to them, and the form of social organization which they elaborated in Eastern Pennsylvania still persists. This social organization has varying characteristics. It is somewhat difficult to analyze the intricate windings and entanglements of doctrinal and practical belief in custom among the Mennonites, Amish and Dunkers. Old school and new school have been formed in almost every one of these sects. Eccentric and peculiar principles of belief in organization have formed the lesser and the least permanent groups; but there is a common principle in them all. Their ability to form communities in the midst of hostile populations and adverse conditions has been due to the co-operation between their religious and their economic habits.