Great theologian of Baghdad who gave definitive expression to Islam, and brought Sufism into the mainstream of piety. Ghazali a protégé of vizier Nizamulmulk, was appointed a lecturer, in 1091, at the Nizamiyyah madrasah in Baghdad was an expert in Islamic law and was also known as Hujjat-ul-Islam. He suffered a nervous breakdown in 1095 and was distressed by the possibility of losing his faith. He was paralysed and could not speak and was diagnosed having a deep-seated emotional conflict. Ghazali later explained that he was concerned that though he knew a great deal about Allah, but he did not know Allah himself. Ghazali wandered as ascetic at different places (this was a process of mystical transformation) and finally reached Jerusalem, where he practised Sufi exercises. Ghazali, after a decade, returned to Baghdad and wrote his masterpiece Ihyah al-ulum al-Islamia (The Revival of the Religious Sciences). The book was based on the important insight that only ritual and prayer could give human beings a direct knowledge of Allah - the arguments of theology and Falsafah could give no certainty about the divine. He argued that Ihyah provides Muslims with a daily spiritual and practical regimen, designed to prepare them for this religious experience. Thus Shariah had become more than a means of social conformity, and a slavish exterior imitation of the Prophet, peace be upon him, and his Sunnah - a way of achieving interior Islam. Ghazali argued that dependence upon an authority figure seemed to violate the egalitarianism of the Qura'an. Falsafah, he acknowledged, was indispensable for such disciplines as mathematics or medicine, but it could give no reliable guide to spiritual matters that lie beyond the use of reason. In Ghazali's view, Sufism was the answer, because its disciplines could lead to a direct apprehension of the divine. He urged to practise the contemplative rituals that the Sufi mystics had developed and to promote this interior spirituality at the same time as they propagated the external rules of Shariah. Both were crucial to Islam. Thus Ghazali had given mysticism a ringing endorsement, using his authority and prestige to assure its incorporation into mainstream Muslim life. Ghazali was one of the greatest and most celebrated doctors, and authored Ahia ul ulum, Kimaiae Sa'adat, Tafsir Jawahir ul Qur'an, Tuhafut al-Falasifa (The Incoherence of the Philosophers), al Iqtisad fi al Itiqad and many other works. His masterpiece Ihyah al-ulum al-Islamia (The Revival of the Religious Sciences) was translated into Latin in 1150, and influenced scholars like Thomas Aquinas and Pascal. Ghazali's autobiographical work is called Al Munqidh min az Zalal (The Deliverer from Error). Al-Ghazali was one of the greatest theologians of Islam and his doctrines penetrated Europe and influenced Jewish and Christian scholasticism. So forceful was his argument in the favour of religion that he was accused of damaging the cause of philosophy and, in the Muslim Spain, Ibn Rushd (Averros) wrote a rejoinder to his Tuhafut. Al-Ghazali was born Abu Hamid Ibn Muhammad Ibn Zainuddin al-Tusi al-Shafi'i al-Ghazali at Khorasan, Iran. He believed that there were three sorts of people. Firstly, those who accept the truths of religion without questioning them. Secondly, those who try to find justification for their beliefs in the rational discipline of kalam. And thirdly, the Sufi who have a direct experience of religious truth.