Out of the period of social disorder which characterized the early Middle Ages there developed educational movements, such as that which Charlemagne sponsored, and the system of Feudalism, which gave to the Middle Ages its most distinctive set of characteristics. Feudalism made land the central institution of society. The ownership of land gave power; land constituted social and political power. Land was parcelled out upon the receipt of oaths of homage and fealty. Under this land system there were three classes of people: the nobles, the clergy, and the peasants. The nobles were the rulers and exercised military prerogatives. The clergy were either the privileged subjects of the nobles, or else through the institution which they represented they acquired land power. The peasants often despised the nobles, although they worked for and supported them. As an outgrowth of feudal industry various forms of guilds or industrial organizations flourished from the tenth to the fifteenth centuries. Sometimes the masters and workmen jointly belonged to guilds, as in the case of the merchant guilds. Sometimes the guilds became local monopolies. Always they possessed the aim of improving the conditions of the membership. The religious wars, or Crusades, of the eleventh to the thirteenth centuries inaugurated many changes. They gave the restless nobility major themes of attention and even removed many nobles through death in battle from the European arena. They created intellectual unrest. They enlarged the horizons of many individuals and gave rise to skepticism. They led to the Reformation. Social thought in the Middle Ages received a considerable stimulus from Teutonic sources. The barbarous Teutons contributed ideas of freedom. They increased the emphasis upon the individual. They were rough, bold exponents of “personal liberty,” and disregarded mere churchly procedure, social traditions, and some of the finer ideals of life and character. On the other hand, chivalry and knighthood were perhaps of Teutonic origin. The church utilized chivalry. It became the duty of the knight to defend the church and that which belonged to the church. Chivalry became a form of social discipline which ruled in the latter part of the Middle Ages. It softened manners and became the sponsor for virtue. It remained, however, a modified military structure with military traditions. The rise of scholasticism took place in opposition to monasticism. In the ninth century the leading thinkers had not advanced beyond the conception of a natural social state, characterized by chaotic conditions, and organized by political machinery. By the twelfth century only the faintest glimmerings of a doctrine of popular sovereignty had begun to appear. The thought of the day was largely theological.