 As to the recasting of the content of the Metaphysics in The Science of Divine Things, Avicenna quotes all the fourteen books into which the Metaphysics is traditionally divided (apart, perhaps, from book Κ), but according to an order that is strikingly different from that of Aristotle’s work. In The Science of Divine Things, however, Avicenna not only modifies the content of the Metaphysics; he also integrates themes taken from other sources, either from other Aristotelian writings; or from texts belonging to the Greek and Arabic Peripatetic tradition, in which Aristotle’s Metaphysics was commented, elaborated, and expanded; or from his own cultural context. In this last respect, the philosophical theology of The Science of Divine Things includes a series of themes familiar to the Muslim audience of the work (the existence of God, His attributes, providence, theodicy, man’s destiny in the afterlife, prophecy etc.), which are treated on a strictly philosophical basis, but with occasional recourse to examples, terminology, and scriptural quotations of clear Islamic provenance, used to confirm the rational conclusions reached. This, together with the theological views debated throughout the work, indicates Avicenna’s intention to show that the philosophical world-view expressed in metaphysics is not contrary or alien to the Islamic one, and that it can provide rational access to some of the tenets of the Muslim creed. The Science of Divine Things, however, is not the mere sum of its many sources. Within the framework of metaphysics, Avicenna introduces original doctrines, some of which are narrower in scope and occur in localized parts of the work, while others are recurrent and serve to connect and unify its various themes. Most notorious among this latter category are—besides the already mentioned account of the subject-matter of metaphysics—the distinction between essence and existence in created beings, which is the theoretical leitmotif of the work, and the metaphysical proof of God’s existence, grounded in Avicenna’s view of the subject-matter of metaphysics and of causation, and placed at the beginning of the section on philosophical theology (chapters 1–3 of treatise VIII). The distinction between essence and existence is the most famous among Avicenna’s own doctrines and underlies many themes of Avicenna’s metaphysics: it justifies, for instance, the difference between the primary concepts “thing” (i.e., “that which has an essence”) and “existent” at the beginning of the work; it grounds the theory of universals (universality is an attribute that belongs to an essence not as such, but when this latter exists in the human mind, abstracted from the extra-mental things in which it is instantiated); and it leads to the fundamental characterization of God as the only being that has no essence apart from existence, or whose essence is totally identical to its existence. Equally important in The Science of Divine Things is the proof of God’s existence, which is announced at the beginning of the work (I.6) and completed towards its end (VIII.1–3). It involves a precise view of the relationship between metaphysics and natural philosophy, being properly metaphysical and independent from the conclusions reached in physics; it turns out to be original with regard to the other metaphysical writings of Avicenna, because it is based not only on a precise doctrine of the Metaphysics (the finiteness of causal chains in Metaph. α, 2), but also on the text itself of this chapter of Aristotle’s work, as we have seen.