  The “true philosophy” that Ibn Daud expounds is the form of Aristotelianism, which was articulated by the Muslim philosophers Alfarabi and especially Ibn Sina. Ibn Daud refers to Alfarabi’s commentary on Aristotle’s Topics and seems to have been familiar with his commentary on the Categories as well. In general, Ibn Daud was influenced by Alfarabi’s thought as presented in as-Siyâsât al-madaniyya (The Political Regime). Even more important for Ibn Daud’s system was Ibn Sina’s thought. Many of the demonstrations in the ER are based on works by this author, in particular his encyclopedic works Kitâb al-Shifâ’ and Kitâb an-Najât. Most influential was Ibn Sina’s psychology, as well as his views of the Necessary Being, cosmology and the origin of evil.  Ibn Daud also drew on the work of the critic of these philosophers, al-Ghazali (1058-1111) who summarized their teachings in Maqâsid al-Falâsifa (The Intentions of the Philosophers). It is most probable that Ibn Daud’s book reflects al-Najat in its purpose, organization, and language.  Another source of inspiration was the Muslim theologian and polemist Ibn Hazm, whose anti-Jewish polemic inspired Ibn Daud’s Biblical exegesis. As for his Jewish predecessors, Ibn Daud built on Saadya’s Emunot and was certainly familiar with Judah Halevi, although he does not explicitly mention him by name (cf. section 5.7 below).  Occasionally, one also comes across views that he shares with Bahya ibn Paquda, Ibn Zaddiq, or Abraham ibn Ezra.