translation of the Colliget became a medical textbook in Europe for centuries. His other surviving titles include On Treacle, The Differences in Temperament, and Medicinal Herbs. He also wrote summaries of the works of Greek physician Galen (died ) and a commentary on Avicenna's Urjuzah fi al-Tibb ("Poem on Medicine"). Jurisprudence and law Averroes served multiple tenures as judge and produced multiple works in the fields of Islamic jurisprudence or legal theory. The only book that survives today is Bidāyat al-Mujtahid wa Nihāyat al-Muqtaṣid ("Primer of the Discretionary Scholar"). In this work he explains the differences of opinion (ikhtilaf) between the Sunni madhhabs (schools of Islamic jurisprudence) both in practice and in their underlying juristic principles, as well as the reason why they are inevitable. Despite his status as a Maliki judge, the book also discusses the opinion of other schools, including liberal and conservative ones. Other than this surviving text, bibliographical information shows he wrote a summary of Al-Ghazali's On Legal Theory of Muslim Jurisprudence (Al-Mustasfa) and tracts on sacrifices and land tax. Philosophical ideas Aristotelianism in the Islamic philosophical tradition In his philosophical writings, Averroes attempted to return to Aristotelianism, which according to him had been distorted by the Neoplatonist tendencies of Muslim philosophers such as Al-Farabi and Avicenna. He rejected al-Farabi's attempt to merge the ideas of Plato and Aristotle, pointing out the differences between the two, such as Aristotle's rejection of Plato's theory of ideas. He also criticized Al-Farabi's works on logic for misinterpreting its Aristotelian source. He wrote an extensive critique of Avicenna, who was the standard-bearer of Islamic Neoplatonism in the Middle Ages. He argued that Avicenna's theory of emanation had many fallacies and was not found in the works of Aristotle. Averroes disagreed with Avicenna's view that existence is merely an accident added to essence, arguing the reverse; something exists per se and essence can only be found by subsequent abstraction. He also rejected Avicenna's modality and Avicenna's argument to prove the existence of God as the Necessary Existent. Averroes felt strongly about the incorporation of Greek thought into the Muslim world, and wrote that "if before us someone has inquired into [wisdom], it behooves us to seek help from what he has said. It is irrelevant whether he belongs to our community or to another". Relation between religion and philosophy During Averroes's lifetime, philosophy came under attack from the Sunni Islam tradition,