The primary source for surma is the Hadith, a written collection of say- ings attributed to Muhammad. Each hadith had to go through a rigorous verifica- tion process before it was accepted as truth; the tale had to be verified by several sources, preferably those who saw the action with their own eyes, and the greatest weight was given to testimony by Muhammad's close followers. Islam continued to grow after the Prophet's death, flourishing in the "Age of Con- quest" who succeeded Muhammad led wars against apostate nomadic tribes. Faith in Islam was the strength of the Arab armies, which defeated the once-mighty Persian empire by the year 640. The fourth Caliph, Muhammad's nephew and son-in-law AU, was the cata- lyst for the major split in the Muslim world. Ah slowly lost power and was mur- dered in 661. The Shi'at AU believe Ali, as a blood relative of the Prophet, to be the only legitimate successor to Muhammad, thus sep- arating themselves from Sunni Muslims. Contrary to popular Western perception, Shi'ite MusUms are not fanatics, but rather Muslims with a sharp focus on divinely chosen leaders who are blood descendants of the Prophet through AU. In the 10th century, under the weight of tradition and consensus, Sunni Muslim scholars " closed; new concepts and interpretations could no longer stand on their own but had to be legitimized by tradition. This proscription notwithstanding, ijtihad continues today, as within several generations the formal prohibition against forward think- ing was removed. There have been numerous reform movements throughout the Islamic world, including the Wahhabbi movement in the Arabian peninsula, the movement of the thinker Jamal al-Din al-Afghani in the Middle East, and Muham- mad Iqbal in South Asia. There are four main schools of thought in the Islamic legal system, and the appUcability of sharia, or Islamic law, is a subject of much strife in a number of Muslim countries, which have seen challenges to entrenched governments by movements carrying the banner of Islam. The Sufis are a mystical movement within Islam, stressing the goal of unity with God. They are organized in orders, with a clear hierarchy from master to disciple. Different orders prescribe different ways of life in order to reach Allah; some preach total asceticism and others seem almost hedonistic in their pursuit of plea- sure. Sufi sheikhs and saints are reputed to perform miracles, and their tombs are popular pilgrimage destinations. Jalal al-Din Rumi, the great medieval intellectual, founded the famous order of the whiriing dervishes. The term "whirl- ing dervish" derives from the joyous spinning and dancing meant to produce a state of mind conducive to unity with Allah. Substances such as wine were often used for similar purposes, though the great poets like Rumi treat the effects of alcohol more as a metaphor for the individual's journey with God. FIVE PILLARS OF ISLAM. Ash-hadu an la ilaha ilia Allah.