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Proclus Lycaeus (February 8, 412 - April 17, 485), surnamed "The Successor" or "diadochos" (Greek Πρόκλος ὁ Διάδοχος Próklos ho Diádokhos), was the last major Greek Neoplatonist philosopher. His systematized and refined the cosmologies of Plotinus and Iamblichus, and produced one of the most elaborate, complex, and fully developed Neoplatonic systems. His careful documentation of early Greek mathematicians in his commentary on Euclid’s Elements of Geometry is a valuable historical source.

Proclus’ greatest concern was the elevation of the human soul to unity with its divine origins. Believing that reason could dominate the physical passions but was incapable of grasping higher levels of spiritual knowledge, he promoted theurgy, the use of material objects and mathematical symbols in religious rites intended to awaken the soul to its own divinity. His works influenced later Christian (Greek and Latin), Islamic, and Jewish thought. His ideas were adapted by Pseudo-Dionysius to add a new dimension to Christian theology, and translations of his works were widely studied by medieval and Renaissance scholars.


Proclus was born 410 or 411 C.E. (his birth year is deduced from a horoscope cast by a disciple, Marinus) in Constantinople to a high-ranking family from Lycia. His father, Patricius, was a prominent legal official in the court system of the Byzantine Empire. Proclus was raised in Xanthus, on the south coast of Lycia. He went to Alexandria, in Egypt, and studied rhetoric, philosophy, and mathematics with the intention of pursuing a judicial position like his father. During his studies, he returned to Constantinople with his mentor Leonas, who had business there, and successfully practiced law for a short time. From this experience he realized that he preferred philosophy to law. He returned to Alexandria, and began a determined study of the works of Aristotle under Olympiodorus the Elder, and of mathematics under a teacher named Heron (no relation to Hero of Alexandria).

Eventually, dissatisfied with the level of philosophical instruction available in Alexandria, Proclus went to Athens in 431 to study at the Academy founded eight hundred years earlier (387 B.C.E.) by Plato. There he was taught by Plutarch of Athens and Syrianus; in 450 he succeeded Syrianus as head of the Academy and received the title diadochus ("successor" to Plato). He lived in Athens for the remainder of his life, except for one year of voluntary exile to escape political pressures. He spent his exile traveling in Asia and being initiated into various mystery cults, before returning to his post at the Academy in Athens. His biographers report that he was very active; every day he gave five lectures or discussions, and wrote seven hundred lines. Proclus never married; he was prosperous, gave generously to his friends, and was much sought after as a scholar and adviser. He was a vegetarian and practiced theurgy and a number of religious rites, including the annual observation of the birthdays of Plato and Socrates, fasting in honor of the Egyptian gods, and monthly ceremonies for the Great Mother. Simplicius, writing one hundred years later, reported that all of the philosophers who associated with Proclus accepted his doctrine except for his student Asclepiodorus, who remained a free thinker and skeptic.

Proclus died April 17, 485, and was buried in a tomb next to his teacher Syrianus, not far from Mount Lycabettus. An epigram on the tomb reads: "I am Proclus, Lycian whom Syrianus brought up to teach his doctrine after him. This tomb reunites both our bodies. May an identical sejourn be reserved to our both souls!"


Proclus was a systematic writer, able to sustain clarity through long and elaborate explanations. His works provided a careful recapitulation of the views of his predecessors, as well as his own astute analysis. Since many of his original sources were later lost, his writings provide a valuable record of ancient thought.

Proclus believed the true philosopher should pay homage to the gods of all nations, and become "a priest of the entire universe." He defended paganism and opposed Christianity, with its doctrine that the world was finite. His open-minded approach gave his philosophical system a richness and depth that provided inspiration for many future thinkers.

The majority of Proclus' works are presented as commentaries on the dialogues of Plato (Alcibiades, Cratylus, Parmenides, Republic, Timaeus). Like other Neoplatonists, Proclus presented his own philosophical system, which was much more elaborate and complex, as a faithful interpretation of Plato. He considered the Platonic texts to be divinely inspired (ho theios Platon, “the divine Plato”), and believed that they contained a deeper meaning which was hidden from the philosophically uninitiated.

Proclus also wrote a valuable commentary on the first book of Euclid's Elements of Geometry. This commentary is one of the most complete surviving sources for the history of ancient mathematics, presenting an overview of one thousand years of Greek mathematics. Its Platonic account of the status of mathematical objects was very influential.

In addition to his commentaries, Proclus wrote two major systematic works. The Elements of Theology is a singular work in the history of ancient philosophy. It consists of 211 Neoplatonic 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 systematization of material from Platonic dialogues, illustrating the characteristics of the divine orders, the part of the universe closest to the One.

Hypotyposis introduced the astronomical theories of Hipparchus and Ptolemy and described the mathematical theory of the planets based on epicycles and on eccentrics. Proclus gave a geometrical proof that the epicycle theory of planetary movement (in which Earth is the center of a circle with smaller circles rotating around its circumference) is equivalent to the eccentric theory (in which the planets move in circles which do not have Earth as the center).

Three small works, Ten Doubts Concerning Providence, On Providence and Fate, and On the Existence of Evils are extant only in Latin translation.

Proclus was a poet as well as philosopher and mathematician, and wrote a number of religious hymns.



Proclus, like the other Neoplatonists, combined Platonic, Aristotelian, and Stoic elements in his thought. He refined and systematized the elaborate metaphysical speculations of Iamblichus. In contrast to the skeptic position that the material universe is outside the human consciousness and can only be known through sensory impressions, the Neoplatonists emphasized the underlying unity of all things and placed the human soul and the material universe in a hierarchy of emanation from a universal being, in which every level is a reflection of that being.

The One

In Neoplatonism, the first principle is the One (to Hen). Since the One produces all Being, it cannot itself be a being. The One is also beyond thought, because thinking requires the determinations which belong to being: The division between subject and object, and the distinction of one thing from another. Even the appellation "the One" is derived from his own inadequate conception of the simplicity of the first principle. The One confers unity on all things through forms, the intangible essences (ideas) which give each being its unique qualities. Neoplatonists thought of the One as the source of the good, or perfection, of everything.

Proclus inserted a level of individual “ones,” called henads between the ultimate One 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.

The “One” of Proclus resembles a combination of the Platonic Form of the Good, which confers being and intelligibility on all things, and Aristotle's Unmoved Mover, which is the "final cause" of all things.

Between the One and the henads (some scholars place it after the henads) are the two principles of First Limit (peras, oneness) and First Infinity (apeiron).


According to Proclus, the One produces a divine mind, Intellect (nous), which exists below the level of the henads. Intellect is both Thinking and Being. As Being, Intellect is the product of the One. In Thinking, the Intellect attempts to grasp its cause, the One, as its Good (perfection). The simplicity of the One does not allow the Intellect to grasp it, so the Intellect generates a succession of different perspectives of the One, which are the Platonic Forms, the first determinations into which all things fall.

Plotinus and Iamblichus spoke of the Intellect’s attempt to return to the One by Thinking as a form of desiring. Proclus systematized this concept into a three-fold motion of remaining (or abiding), procession, and return (mone, proodos, epistrophe). Intellect remains in the One, as its origin. It proceeds from the One, coming into being as a separate entity. Simultaneously it returns to the One, so that it does not separate from its source, but receives its identity, its good (ideal state of being), from the One. Proclus extended this three-fold motion of remaining, procession, and return to all the levels of being between the One and matter.

Proclus elaborated his account of Intellect much farther than Plotinus had. Plotinus’ account of Intellect distinguished between Being and Thinking; Proclus added a third distinction in keeping with the structure of remaining, procession, and return. Intellect was distinguished into Intellectual (the thinking subject), Intelligible (the object of thought), and Intelligible-Intellectual (the capacity of the object to be grasped by the thinking subject). These three distinctions were further elaborated: The intelligible was a triad of Being, Eternity, and the Living Being (or Paradigm, from Plato's Timaeus); the intelligible-intellectual moment was also a triad; and the intellectual moment was a hebdomad (seven elements) including the Demiurge from Plato's Timaeus and also the monad of Time (which is before temporal things). Proclus attempted give a hierarchical order to the various metaphysical elements and principles of earlier philosophers have discussed.

Proclus' universe unfolded from unity to multiplicity in the smallest possible steps. With Intellect emerged the multiplicity which allowed one being to be different from another being. As a divine mind, Intellect had a complete grasp of all its moments in one act of thought, and was therefore outside of Time. As the second principle, Intellect also gave rise to individual intellects which occupied various positions within the cosmos. Each level of the hierarchy “participated” in the level above it, and each level had a “universal” aspect, its Unparticipated Monad, which which was the culmination and unity of all the levels below it.


Soul (Psyche) was the third principle in the Neoplatonic system, produced by Intellect. Like Intellect, it was a mind, but it did grasp all of its own content as once. Therefore Time came into existence, as a measure of Soul's movement from one object of thought to another. Intellect tried to grasp the One, and produced its own ideas as its content. Soul attempted to grasp Intellect in its return, and ended up producing its own secondary unfoldings of the Forms in Intellect. Soul, in turn, produced Body, the material world.

In his commentary on Plato's Timaeus Proclus explained the role of the Soul as a principle in mediating the Forms in Intellect to the body of the material world. 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 had the same basic structure as the principle of Soul, but they were fascinated with the material world, overpowered by it, and united with a material body through birth. In an embodied soul, passions had a tendency to overwhelm reason. According to Proclus, philosophy was the activity which could liberate the soul from being subject 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.

The highest goal, however, was not the elevation of reason, but unity of the individual soul with the Intellect. The faculty of reason belonged to the level of the individual soul and therefore could not elevate it beyond this level. Proclus believed that the practice of theurgy directed the attention of an embodied soul towards its origin in the intelligible world. The characteristics of the gods (the henads) were imprinted on each level of their series of causation down to the material world. By contemplating certain objects and symbols, and performing certain rites, the soul could rediscover these characteristics in itself and gradually ascend the causal series to its origin. The rites of theurgy also attracted the assistance, or elevating power, of the appropriate henads. Proclus himself was a devotee of all of the pagan cults in Athens, considering that the power of the gods was present in all these various ways.


For Neoplatonists, an understanding of the cosmos was a necessary guide to achieving a life of goodness, and therefore, happiness. Since the “One” was also the “Good,” the goodness of anything could be determined by how well it reflected its origin and fulfilled its purpose in nature. Proclus took an interest in diverse subjects, and also perceived music and literary works such as Homer as sources of truth.


Proclus was the last major Greek philosopher, and was influential in spreading Neoplatonic ideas throughout the post-pagan Byzantine, Islamic, and Roman worlds.

Proclus' works had a great influence on the history of western philosophy. Around 500 C.E., a Christian Neoplatonist presenting himself as Dionysius the Aeropagite, an Athenian convert of St. Paul, wrote several treatises and letters adapting Proclus’ cosmology and his ideas regarding religious purification to a Christian world view. The writings of Pseudo-Dionysius were regarded as having almost apostolic authority, and made their way into the doctrine of the Christian church.

Boethius's (480–525) Consolation of Philosophy, written in prison while awaiting execution, contains several principles and themes drawn from Proclus. The central poem of Book III is a precis of Proclus' Commentary on the Timaeus, and Book V contains the principle that things are known not according to their own nature, but according to the character of the knowing subject. Consolation of Philosophy was popular at the court of King Charlemagne during the ninth century and was later translated into English by Chaucer. It was studied throughout Europe from the fifteenth century onwards.

A summary of Proclus' Elements of Theology circulated under the name Liber de Causis (the Book of Causes) in the Arabic world as a work of Aristotle. When translated into Latin it had great authority because of its supposed Aristotelian origin, and it was only when Proclus' Elements were translated into Latin that Thomas Aquinas realized its true source. In the thirteenth century, William of Moerbeke's Latin translation of the Elements of Theology (as Institutio Theologica) became the principal sources for medieval knowledge of Platonic philosophy, and helped to lay the foundation for the Renaissance revival of Neoplatonism.

The German-Jewish scholar Leo Baeck (1873-1956) suggested that the Gnostic-Proto-Kabbalistic text, the Sefer Yetzirah, "in its thought as well as in its terminology, is dependent upon the teaching of Proclus, the last great Neoplatonist. Furthermore, the decisive passages of the Sefer Yetzirah are none other than the transference of this Greek scholastic's system into Jewish thought and biblical language."

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 ardent promoter of Proclus in the English speaking world was Thomas Taylor, who produced English translations of a number of his works.

The works of Proclus 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."

The Moon's Proclus Crater is named after him.


Proclus' Works

  • Platonic Theology: A long (six volumes in the Budé edition) systematic work, using evidence from Plato's dialogues to describe the character of the various divine orders
  • Elements of Theology: A systematic work, with 211 propositions and proofs, describing the universe from the first principle, the One, to the descent of souls into bodies
  • Elements of Physics
  • Commentary on Plato's "Alcibiades I" (it is disputed whether or not this dialogue was written by Plato, but the Neoplatonists thought it was)
  • Commentary on Plato's "Cratylus"
  • Commentary on Plato's "Parmenides"
  • Commentary on Plato's "Republic"
  • Commentary on Plato's "Timaeus"
  • Commentary on the first book of Euclid's "Elements of Geometry"
  • Three small works: Ten Doubts Concerning Providence; On Providence and Fate; On the Existence of Evils
  • Various Hymns (fragments)
  • Commentary on the Chaldaean Oracles (fragments)
  • The Life of Proclus, or On Happiness: written by his pupil, Marinus

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 Causis) is not a work by Proclus, but a précis 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.

ISBN links support NWE through referral fees

  • Bos, E. P. and P.A. Meijer (Eds). On Proclus and His Influence in Medieval Philosophy. (Philosophia antiqua 53), Leiden-Köln-New York: Brill, 1992.
  • Cleary, J. The Perennial Tradition of Neoplatonism. Leuven: Leuven University Press, 1997.
  • Dodds, E. R. (Ed). The Elements of Theology: A Revised Text with Translation, Introduction, and Commentary. Oxford University Press, 1992.
  • Proclus; Morrow, Glenn R. (Translator). Proclus. Princeton University Press; Reprint edition, 1992.
  • Proclus; Morrow, Glenn R. (Translator), Dillon, John M. (Translator). Proclus' Commentary on Plato's "Parmenides." Princeton University Press; Reprint edition, 1992.
  • Siorvanes, Lucas. Proclus: Neo-Platonic Philosophy and Science. Yale University Press, 1997.
  • Taylor, Thomas. Proclus the Neoplatonic Philosopher. Kessinger Publishing; Facsimile Ed edition, 1997.
  • Taylor, Thomas. Commentaries of Proclus on the Timæus of Plato, Part 1. Kessinger Publishing, 2002.

External links

All links retrieved November 30, 2022.

General Philosophy Sources


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