Obliged to return to England in 1684, Penn did not again visit his American possessions until fifteen years had elapsed, and then but for a brief time (1699-1701). This intervening period was one of continuous political disquiet for the proprietor and the colonists alike, despite the fact that the material condition of the people--Quakers, Swedes, Dutch, Germans, and Welsh alike--continued to improve. A boundary dispute with Maryland required the intervention of the English government (1685) as an arbitrator; during two years (1692-1694), Penn was dispossessed of his colony by the Crown; and the turbulent "territories" gave him so much trouble that he sought peace by erecting them into the separate colony of Delaware in 1703. Dissensions, however, did not cease either in the provinces or in Delaware. Penn died in 1718, leaving to his heirs a legacy of petty but harassing disputes which lasted until the Revolution. Sidenote: Characteristics of Pennsylvania. Planted as Pennsylvania was, half a century after the earlier Southern and New England colonies, and aided by rich men and court favorites, its progress was rapid and its prosperity assured from the beginning. The pacific policy of Penn towards the Indians saved his colony from the expense and danger of frontier wars. Nevertheless from the beginning the colony showed the same indisposition to submit to the control of proprietors that had so disturbed Maryland and the Carolinas. Notwithstanding, Pennsylvania shortly became the most considerable of the middle colonies, and eventually equalled Virginia and Massachusetts in importance. CHAPTER X. SOCIAL AND ECONOMIC CONDITIONS IN THE MIDDLE COLONIES IN 1700. 90. References. Bibliographies.--Same as § 82, above. Historical Maps.--Same as § 82, above. General Accounts.--Doyle, _Colonies_, IV.; Lodge, _Colonies_, chs. xiii., xv., xvii.; Andrews, _Colonial Self-Government_, chs. xviii., xix. See also histories of separate colonies, § 82, above. Special Histories.--Topography: Semple, _American History and its Geographic Conditions_, chs. i.-iv.; Roberts, _New York_, I. ch. viii.; Scharf, _Delaware_, ch. i.--Manners and Customs: Fisher, _Men, Women, and Manners in Colonial Times_, I. chs. vi., vii., II. ch. viii.; Wilson, _Rambles in Colonial Byways_; Earle, _Colonial Days in Old New York_; C. Hemstreet, _When Old New York was Young_; T. Janvier, _Old New York_; E. Singleton, _Dutch New York_; J. Van Rensselaer, _Goede Vrouw of Mana-ha-ta_; A. Gummere, _The Quaker: a Study in Costume_; novels by S. W. Mitchell.--Industries: Bishop, _History of American Manufactures_.--Slavery: J. Brackett, _Negro in Maryland_. See also § 82, above, and biographies of prominent men. Contemporary Accounts.--Same as § 82, above. 91. Geographical Conditions in the Middle Colonies. Sidenote: Geography.