Various other thought elements appeared in the closing centuries of the Middle Ages. As early as the ninth century a maritime code, a military code, and a rural code were formulated in the Byzantine Empire in order to meet new social needs. Until the fall of Constantinople the Byzantine influence was a deterrent against the forces from the East. Byzantium preserved and gave a new impetus to Grecian literature, art, architecture, and law. In Arabia the celebrated historian and philosopher Ibn Khaldun (1332–1406), made a detailed and surprisingly accurate description of the social life of the Arab tribes. With the evolution of the life of the individual, he compared the development of the successive stages in social life. This distinguished historian urged that history should consider not simply rulers, dynasties, and wars, but also racial factors, climatic forces, the laws of association, and the stages of associative life. He wished to make history scientific, even a social science. He formulated an evolutionary doctrine of social progress. He evolved a spiral theory of social evolution, beginning with the crudest primitive life and ending with the most civilized urban life. In the latter part of the fourteenth century, England’s great popular poet, William Langland, wrote an allegorical poem entitled, _Piers Ploughman_. In this work the oppressed laboring and peasant classes cry aloud their longings for improved conditions. They are personified in Piers the Ploughman, who as a dignified laborer, plays for the first time the leading rôle in serious thought. He is the leader of a field of all types of people who are laboring together and longing for a better social order. Along with the agricultural laborers we see weavers and tailors, friars and minstrels, merchants and knights. Labor of every sort is dignified. All living laborers who work with their hands and minds, truly earning, living in love and according to the laws of social order and progress, will become the pure and perfected leaders of truth. Langland depicted well the living and working conditions of the English laboring classes. Productive toil, he argued, will receive its crown of glory. But he did not indicate practical solutions. Langland was sure, however, that the service of labor to society is sacred. He pronounced patient poverty to be the prince of all virtues. He personified Jesus in the form of a working man. Langland’s fourteenth century social message was that the individual should renounce wealth, join the honest laboring poor, and follow Christ’s example of living a life of labor and love.[IX-1]