An Analysis of Reason and Revelation in al-Tawhidi's Epistle On [the Classification of] Knowledge (Risala fi al-'Ulum) This paper assesses the roles that al-Tawhidi ascribes to the Qur'an and reason as sources for moral enquiries. Both sources will be discussed through an analysis of al-Tawhidi's epistle Rissla fs al-'Ulum within its socio-political and intellectual contexts, including the debate in tenth-century Buyid society over scepticism about valid sources of knowledge. Also treated will be his al-Muqabasat in which he deals with similar issues. Al-Tawhidi attempted to reconcile contemporary intellectual tensions about the divided status of scholarly disciplines in order to fit them all into a cohesive framework. Refuting the view that logic has nothing to do with religious law, al-Tawhidi relates 'arabiyya (Arabic religious science) to a broader context, offering a view of perfection where knowledge of this science is integrated with logic and Greek philosophy. Thus he ascribes numinous qualities to 'arabiyya as the language of the Qur'an, also making explicit the juristic prerogative in the proper understanding of the use of Arabic. Al-Tawhidi classifies the forms of knowledge as: 1) Jurisprudence, which deduces religious law on the basis of the Qur'an and the Prophet's sunna; 2) Qiyas (Analogy); 3) Kalam (Theology), assuming that its methods avoid hypocrisy and extremism; 4) Grammar, Lexicography, and Eloquence, which assume a set of values that determines social behaviour, reflecting one's religio-cultural identity; 5) Logic; 6) Medicine; 7) Astronomy, which leads to appreciation of God's creation; 8) Mathematics; and 9) Tasawwuf. Al-Tawhidi's use of both religion and philosophy as valid paths to truth shifted the focus in determining the validity of knowledge from a normative value of revealed or non-revealed knowledge to a basis of the practical moral value of knowledge and its societal function for the well-being of the community. This classical Islamic model can serve as an example for Muslims' current attempts to define the place of the sacred and human reason in their relationship with the modern world.