 In al-Fārābī’s main works on political philosophy, philosophical theology is the only part of metaphysics that functions as preliminary—together with human noetics, man’s destiny in the after-life, and prophecy—to the account of the organization of the ideal state (Principles of the Opinions of the Inhabitants of the Virtuous City, Mabādiʾ Ārāʾ Ahl al-Madīna al-Fāḍila). Other works of his, on the other hand, deal specifically with ontological themes. Among them, the Book of Letters (Kitāb al-Ḥurūf, which is not, properly speaking, a commentary on the Metaphysics, despite the title echoing one of the Arabic names of Aristotle’s work) follows a pattern analogous to that of Book Delta (V) of the Metaphysics; the treatise On One and Unity (Fī l-wāḥid wa-l-waḥda) is thematically linked to Book Iota (X); the refutation of Philoponus’ criticism of Aristotle is a reassessment of the thesis of the eternity of the world. Scattered references to the Metaphysics, with regard to distinct topics, surface also in the famous Book on the Agreement of the Opinions of the Two Sages, the Divine Plato and Aristotle (Kitāb al-Ǧamʿ bayna raʾyay al-ḥakīmayn Aflāṭūn al-ilāhī wa-Arisṭūṭālīs), which resumes the Porphyrian theme of the harmony between Aristotle’s and Plato’s views, that had been taken up by al-Kindī and Ṯābit ibn Qurra, but seems alien to Fārābī’s conception of the history of philosophy. For this and other reasons, the Farabian authorship of this treatise, despite the manuscript evidence, has been repeatedly questioned in recent scholarship.