See Fragments of the Lost Writings of Proclus (ed. by R. Navon, tr. by T. Taylor, 1987).
Proclus Lycaeus (February 8, c. 411 – April 17, 485), called "The Successor" or "Diadochos" (Greek Πρόκλος ὁ Διάδοχος Próklos ho Diádokhos), was a Greek Neoplatonist philosopher, one of the last major Classical philosophers (see Damascius). He set forth one of the most elaborate and fully developed systems of Neoplatonism. He stands near the end of the classical development of philosophy, and was very influential on Western Medieval Philosophy (Greek and Latin) as well as Islamic thought.
Actually experiencing the practice of law made Proclus realize that he truly preferred philosophy. He returned to Alexandria, and began determinedly studying the works of Aristotle under Olympiodorus the Elder (he also began studying mathematics during this period as well with a teacher named Heron- no relation to Hero of Alexandria who was also known as Heron). Eventually, this gifted student became dissatisfied with the level of philosophical instruction available in Alexandria, and went to Athens, the preeminent philosophical center of the day, in 431 to study at the Neoplatonic successor of the famous Academy founded 800 years (in 387 BCE) before by Plato; there he was taught by Plutarch of Athens, Syrianus, and Asclepigenia; he succeeded Syrianus as head of the Academy, and would in turn be succeeded on his death by Marinus of Neapolis. He died aged ~73, and was buried near Mount Lycabettus in a tomb.
He lived in Athens as a vegetarian bachelor, prosperous and generous to his friends, until the end of his life, except for a voluntary one year exile, which was designed to lessen the pressure put on him by his political-philosophical activity, little appreciated by the Christian rulers; he spent the exile travelling and being initiated into various mystery cults as befitted his universalist approach to religion, trying to become "a priest of the entire universe." He had a great devotion to the Goddess Athena, whom he believed guided him at key moments in his life. Marinus reports that when Christians removed the statue of the Goddess from the Parthenon, a beautiful woman appeared to Proclus in a dream and announced that the "Athenian Lady" wished to stay at his home.
Proclus also wrote an influential commentary on the first book of Euclid's Elements of Geometry. This commentary is one of the most valuable sources we have for the history of ancient mathematics, and its Platonic account of the status of mathematical objects was influential. In this work, Proclus also listed the first mathematicians associated with Plato: a mature set of mathematicians (Leodamas of Thasos, Archytas of Taras, and Theaetetus), a second set of younger mathematicians (Neoclides, Eudoxus of Cnidus), and a third yet younger set (Amyntas, Menaechmus and his brother Dinostratus, Theudius of Magnesia, Hermotimus of Colophon and Philip of Opus). Some of these mathematicians were influential in arranging the Elements, that Euclid later published.
In addition to his commentaries, Proclus wrote two major systematic works. The Elements of Theology, which consists of 211 propositions, each followed by a proof, beginning from the existence of the One (the first principle of all things) and ending with the descent of individual souls into the material world. The Platonic Theology is a systematisation of material from Platonic dialogues, showing from them the characteristics of the divine orders, the part of the universe which is closest to the One.
We also have three essays, extant only in Latin translation: Ten doubts concerning providence; On providence and fate; On the existence of evils.
He also wrote a number of minor works, which are listed in the bibliography below.
There is a double motivation found in Neoplatonic systems. The first is a need to account for the origin and character of all things in the universe. The second is a need to account for how we can know this origin and character of things. These two aims are related: they begin from the assumption that we can know reality, and then ask the question of what reality must be like, in its origin and unfolding, so that we can know it. An important element in the Neoplatonic answer to these questions is its reaction to Scepticism. In response to the sceptical position that we only know the appearances presented by our senses, and not the world as it is, Plotinus placed the object of knowledge inside the soul itself, and accounted for this interior truth through the soul's kinship with its own productive principles.
The particular characteristic of Proclus' system is his insertion of a level of individual ones, called henads between the One itself and the divine Intellect, which is the second principle. The henads are beyond being, like the One itself, but they stand at the head of chains of causation (seirai or taxeis) and in some manner give to these chains their particular character. They are also identified with the traditional Greek gods, so one henad might be Apollo and be the cause of all things apollonian, while another might be Helios and be the cause of all sunny things. The henads serve both to protect the One itself from any hint of multiplicity, and to draw up the rest of the universe towards the One, by being a connecting, intermediate stage between absolute unity and determinate multiplicity.
In terms of his sources, the One is like a combination of the Platonic Form of the Good, because it confers being and intelligibility on all things, and Aristotle's Unmoved Mover, which is the final cause of all things.
Coming between the One and the henads (some scholars think after the henads) are the two principles of First Limit and First Infinity, which are the principles of the fertile production (Infinity or Unlimited, apeiron) and the controlled nature of the production (Limit, peras) of all things.
Plotinus speaks about the generation of Intellect from the One, and Intellect's attempt to return to the One in a thinking which is also a desiring. Proclus systematises this production through a threefold movement of remaining, procession, and return (mone, proodos, epistrophe). Intellect remains in the One, which means that it has the One as its origin. It proceeds from the One, which means that it comes to be as a separate entity. But it returns to the One, which means that it doesn't cut itself off from its source, but receives the good which is its identity from the One. This threefold motion is used by Proclus to structure all levels of his system below the One and above material reality, so that all things except those mentioned remain, proceed, and return.
Proclus also gives a much more elaborate account of Intellect than does Plotinus. In Plotinus we find the distinction between Being and Thinking in Intellect. Proclus, in keeping with his triadic structure of remaining, procession, and return, distinguishes three moments in Intellect: Intelligible, Intelligible-Intellectual, and Intellectual. They correspond to the object of thought, the power of the object to be grasped by the subject, and the thinking subject. These three divisions are elaborated further, so that the intelligible moment consists of three triads (Being, Eternity, and the Living Being or Paradigm from Plato's Timaeus). The intelligible-intellectual moment also consists of three triads, and the intellectual moment is a hebdomad (seven elements), among which is numbered the Demiurge from Plato's Timaeus and also the monad of Time (which is before temporal things). In this elaboration of Intellect as a whole, Proclus is attempting to give a hierarchical ordering to the various metaphysical elements and principles that other philosophers have discussed, by containing them within a single triadic logic of unfolding.
Proclus' universe unfolds according to the smallest steps possible, from unity to multiplicity. With Intellect emerges the multiplicity which allows one being to be different from another being. But as a divine mind, Intellect has a complete grasp of all its moments in one act of thought. For this reason, Intellect is outside of Time.
Intellect as the second principle also gives rise to individual intellects, which hold various places within Proclus' cosmos.
In terms of his sources, Intellect is like taking the Platonic Forms and placing them in the self-thinking thought which is Aristotle's Unmoved Mover.
In his commentary on Plato's Timaeus Proclus explains the role the Soul as a principle has in mediating the Forms in Intellect to the body of the material world as a whole. The Soul is constructed through certain portions, described mathematically in the Timaeus, which allow it to make Body as a divided image of its own arithmetical and geometrical ideas.
Individual souls have the same overall structure as the principle of Soul, but they are weaker. They have a tendency to be fascinated with the material world, and be overpowered by it. It is at this point that individual souls are united with a material body (i.e. when they are born). Once in the body, our passions have a tendency to overwhelm our reason. According to Proclus, philosophy is the activity which can liberate the soul from a subjection to bodily passions, remind it of its origin in Soul, Intellect, and the One, and prepare it not only to ascend to the higher levels while still in this life, but to avoid falling immediately back into a new body after death.
Because the soul's attention, while inhabiting a body, is turned so far away from its origin in the intelligible world, Proclus thinks that we need to make use of bodily reminders of our spiritual origin. In this he agrees with the doctrines of theurgy put forward by Iamblichus. Theurgy is possible because the powers of the gods (the henads) extend through their series of causation even down to the material world. And by certain power-laden words, acts, and objects, the soul can be drawn back up the series, so to speak. Proclus himself was a devotee of many of the religions in Athens, considering that the power of the gods could be present in these various approaches.
For Proclus philosophy is important, because it is one of the primary ways to rescue the soul from a fascination with the body, and restore it to its station. However, beyond its own station, the soul has Intellect as its goal, and ultimately has unification with the One as it goal. So higher than philosophy is the non-discursive reason of Intellect, and the pre-intellectual unity of the One. Philosophy is therefore a means of its own overcoming, in that it points the soul beyond itself.
Another important source for the influence of Proclus on the Middle Ages is Boethius' Consolation of Philosophy, which has a number of Proclus principles and motifs. The central poem of Book III is a summary of Proclus' Commentary on the Timaeus, and Book V contains the important principle of Proclus that things are known not according to their own nature, but according to the character of the knowing subject.
A summary of Proclus' Elements of Theology circulated under the name Liber de Causis (the Book of Causes). This book is of uncertain origin, but circulated in the Arabic world as a work of Aristotle, and was translated into Latin as such. It had great authority because of its supposed Aristotelian origin, and it was only when Proclus' Elements were translated into Latin that Thomas Aquinas realised its true origin.
Proclus' works also exercised an influence during the Renaissance through figures such as George Gemistios Plethon and Marsilio Ficino. Before the contemporary period, the most significant scholar of Proclus in the English speaking world was Thomas Taylor, who produced English translations of most of his works, with commentaries.
His work inspired the New England Transcendentalists, including Ralph Waldo Emerson, who declared in 1843 that, in reading Proclus, "I am filled with hilarity & spring, my heart dances, my sight is quickened, I behold shining relations between all beings, and am impelled to write and almost to sing."
Modern scholarship on Proclus essentially begins with E.R. Dodd's edition of the Elements of Theology in 1933. Since then he has attracted considerable attention, especially in the French-speaking world. Procline scholarship, however, still (2006) falls far short of the attention paid to Plotinus.
The following epigram is engraved on the tomb which houses Proclus and his master Syrianus:
The Moon's Proclus crater is named after him.
A number of other minor works or fragments of works survive. A number of major commentaries have been lost.
The Liber de Causis (Book of Causes) is not a work by Proclus, but a summary of his work the Elements of Theology, likely written by an Arabic interpreter. It was mistakenly thought in the Middle Ages to be a work of Aristotle, but was recognised by Aquinas not to be so.
Collections of essays