Chapter 25 introduces Alexander of Aphrodisias’ systematic reading of Aristotle’s Metaphysics. I show how Syrianus took over Alexander’s reading of Aristotle, combining it with Plato’s references to a supreme knowledge, ‘dialectic’, and explaining the possibility of scientific knowledge of the objects of metaphysics – transcendent divine first principles – in terms of concepts innate in the soul which both image these first principles and are available to discursive reasoning as sources of knowledge of these principles. The primary text for metaphysics, according to the Platonists, was Plato’s Parmenides. I show how Proclus’ interpretation of the Parmenides, inspired by Syrianus, underlies the composition of Proclus’ metaphysical masterpiece, the Elements of Theology. Finally, Damascius is shown to have brought out to the fullest extent the limits of human reasonings about transcendent divine principles, reasonings which incessantly lead to contradictions and impasses, the aporetical ‘birth-pangs’ of the reasoning soul where it meets what transcend it.