In this concluding chapter, I provide an outline of the Proclan system drawn exclusively from his personal works. I then proceed to compare it to the philosophical system found in Plato’s dialogues along with the testimony regarding it in the Platonic tradition. I examine the two systems under the rubrics: One, Intellect, and Soul. I conclude by arguing that, while Proclus has elevated theology to a place beyond that which Plato himself endorses, nevertheless Proclus emerges as a highly accurate and philosophically sophisticated exegete of Plato and that for the most part, Plato and Proclus stand or fall together philosophically. In the notional Triad: Plato, Platonism, and Proclus, the “middle term” does unite the two “extremes,” even if the logos of each of these is different.

The commentary on Republic is actually a collection of seventeen essays on various topics in Republic. Proclus addresses Plato’s critique of Homer, the tripartitioning of the soul, the nature of the philosopher and his radical distinction from the so-called lovers of sights and sounds, the structure of the divided line, the difference between the superordinate Good and a Form of the Good that is a genus of types of goods, and the taxonomy of decline from the aristocratic man and the aristocratic state, ultimately to the tyrannical man and the tyrannical state. His longest essay is an analysis and meditation on the myth of Er in Republic x, focusing on the nature of wrongdoing and the moral responsibility of the individual. Each of these topics is set within the framework of the Platonic system, at the apex of which is the Idea of the Good or the One whose causal scope is shown to encompass everything that exists, including matter. Thus, epistemological, psychological, and moral problems found in the dialogue need to adduce not only the Good but also the fundamental principles of the system in order to achieve a satisfactory resolution.

This chapter introduces the idea of commentary on the dialogues of Plato as the practice of philosophy in late antiquity. The thesis is advanced that Proclus’ own constructive philosophy is rooted in his exegesis of the Platonic dialogues. Proclus sees his central task as filling in the gaps in the articulation of the Platonic system as found in the dialogues of Plato as well as the testimony in the Platonic tradition. Plato finds gaps in the architectural principles of the system, in drawing out the implications of the major claims for this system, and in the fine-grained analysis of the fundamental technical terms for the expression of the system. Proclus also argues that Plato’s philosophical system is essentially a theological system and that gods, as revealed in the traditional religious literature, need to be subjected to metaphysical analysis. This chapter also surveys how ancient philosophical scholarship understands Proclus’ philosophy and Neoplatonism generally in relation to the philosophy of Plato.

In this chapter, Proclus undertakes a line-by-line analysis of Plato’s dialogue Alcibiades with a view to showing the necessity of self-knowledge for happiness. He argues that self-knowledge is transformative since knowing the self is inseparable from knowing the Good that all desire. Proclus further argues that the Socratic dialectic displayed in this dialogue is an expression of the more profound Platonic dialectic expressed in Republic and elsewhere. In this way, he shows that ethics is inseparable from metaphysics and that Plato’s moral realism pervades even this ‘introductory’ dialogue. The relationship between Socrates and Alcibiades is also explored and is shown to mirror the relationship between the divine Intellect and the kosmos.

In his commentary on the dialogue Parmenides, Proclus examines the challenge posed to the theory of Forms by Parmenides and Zeno. He argues that these challenges can all be met with a grasp of the details of the theory of Forms more sophisticated than that of the young Socrates. Most important, he argues that the second notoriously difficult part of this dialogue both contains the substance of the details necessary for fortifying the theory of Forms and also that it contains Plato’s only systematic expression of his theology. Thus, the theory of Forms is set within the larger metaphysical framework, which is also a theological system. The major philosophical claim Parmenides makes is that the Platonic system needs to posit Henads as ontologically situated between the transcendent One and the intelligible world. These Henads, which are “superessential,” are the fundamental principles of intelligibility that even the Forms participate in. The names for these principles are the philosophical names of the major classes of divine beings. Also in this commentary, Proclus articulates the rationale for a so-called negative theology, since the absolute simplicity of the first principles precludes any predicative judgments made of it.

In this commentary, Proclus address the nature of the Demiurge and shows that he is subordinate to and instrumental to the causal activity of the first principle of all, the Idea of the Good. The Demiurge is not the first principle. His role is as an irreducible instrument of the infusion of goodness into the kosmos. The Demiurge and his causal activity is set alongside the causal activity of the Living Animal, the paradigm employed by the Demiurge in order to bring intelligibility into the sensible world. Proclus here addresses the nature of the causality exercised by the Good and the intelligible world, introducing the concept of triads, which are the paradigms of efficient causal activity here below. Proclus also shows that the “traces” of intelligibility found in the Receptacle of Becoming are evidence of a sort of quasi-intelligibility, which is what occurs when intellect is missing. Thus, the hierarchical causal scope of the elements of the intelligible world is demonstrated. The ultimate causal scope of the Good or One is shown by the existence of matter that is bereft of intelligibility altogether but is indispensable for the instantiation of images of the Forms.

In his commentary on Plato’s Cratylus, Proclus focuses on the theurgical significance of divine names. He argues for the significance of these names as they are revealed in the traditional Greek religious literature and for their evocative power in religion rites. He also discusses the educational importance of correct naming. The connection between the personhood of the gods and their ‘correct’ names is also set within a metaphysical framework.