of public and private life marked by pride, ambition and kinship solidarity, and differing from the married pagan leadership. Unlike later strictures on priestly celibacy, celibacy in Late Antique Christianity sometimes took the form of abstinence from sexual relations after marriage, and it came to be the expected norm for urban clergy. Celibate and detached, the upper clergy became an elite equal in prestige to urban notables, the potentes or dynatoi (Brown (1987) p. 270). The rise of Islam Islam appeared in the 7th century, spurring Arab armies to invade the Eastern Roman Empire and the Sassanian Empire of Persia, destroying the latter. After conquering all of North Africa and Visigothic Spain, the Islamic invasion was halted by Charles Martel at the Battle of Tours in modern France. On the rise of Islam, two main theses prevail. On the one hand, there is the traditional view, as espoused by most historians prior to the second half of the twentieth century (and after) and by Muslim scholars. This view, the so-called "out of Arabia"-thesis, holds that Islam as a phenomenon was a new, alien element in the late antique world. Related to this is the Pirenne Thesis, according to which the Arab invasions marked—through conquest and the disruption of Mediterranean trade routes—the cataclysmic end of Late Antiquity and the beginning of the Middle Ages. On the other hand, there is a more recent thesis, associated with scholars in the tradition of Peter Brown, in which Islam is seen to be a product of the Late Antique world, not foreign to it. This school suggests that its origin within the shared cultural horizon of the late antique world explains the character of Islam and its development. Such historians point to similarities with other late antique religions and philosophies—especially Christianity—in the prominent role and manifestations of piety in Islam, in Islamic asceticism and the role of "holy persons", in the pattern of universalist, homogeneous monotheism tied to worldly and military power, in early Islamic engagement with Greek schools of thought, in the apocalypticism of Islamic theology and in the way the Quran seems to react to contemporary religious and cultural issues shared by the late antique world at large. Further indication that Arabia (and thus the environment in which Islam first developed) was a part of the late antique world is found in the close economic and military relations between Arabia, the Byzantine