PLATONISM AND THE PLATONIC TRADITION

The term "Platonism" is so widely used in modern scholarship that it is difficult to determine its meaning precisely as applicable either to a particular group of thinkers or to a specific collection of doctrines. Ancient sources frequently describe "Platonists" as those philosophers who further developed the known or presumed teaching of Plato himself and "Academics" as those who pursued the skeptical methodology believed to have been initiated by the Socrates of Plato's earlier dialogues. However, the substantive "Platonism" seems first to occur in scholarly literature only around the beginning of the eighteenth century when it was used to characterize doctrines that were not only derived from but also combined with Plato's own teaching by later exegetes.

In order to apply this relatively modern usage of the term "Platonism" legitimately to the history of Western philosophy in general, it is useful to distinguish between: (1) Platonism in the sense of a Platonic tradition, or a set of ideas that is viewed in a strongly historical sense in connection with Plato or his early exegetes and is sufficiently extensive and coherent to overwhelm any influences from other traditions; and (2) Platonism in the sense of a Platonic influence, or a set of ideas that is viewed in a weakly historical sense in connection with Plato or his early exegetes and is not sufficiently extensive or coherent to overwhelm any influences from other traditions. Within the former category, it is useful to distinguish further (a) the direct Platonic tradition, that is, various philosophical ideas which we know to form part of the Platonic legacy and which their proponents characterized similarly, and (b) the indirect Platonic tradition, that is, those philosophical ideas which we know to form part of the Platonic legacy but which their advocates characterized differently.

Throughout the ancient period of Western thought, there was a Platonic tradition when Platonic philosophers were either members of Plato's Academy or claimed to revive and continue the "Academy." For this discussion, the medieval period is considered in terms of distinct Byzantine, Arabic, Jewish, and Latin cultural components, and here the distinction between direct and indirect traditions of Platonism becomes important, especially with respect to the Arabic tradition in which a type of indirect Platonism was viewed as "Aristotelianism." During the modern period of Western thought there has been initially a Platonic tradition, when Platonic philosophers again claimed to revive and continue the "Academy," but subsequently only Platonic influence.

Although such a procedure risks oversimplification, it may be useful to introduce the detailed historical analysis with a statement of the "essence of Platonism," that is, the set of philosophical assumptions underlying Plato's own written works or oral teachings in the view of his immediate successors in the Academy. Scholars may perhaps be guided by the ancient summary of Platonism in Apuleius's On Plato and His Doctrine (2nd century CE), which can be shown to depend on the early Peripatetics and on the early Academy—both with respect to the individual doctrines attributed to Plato and the pedagogical framework presenting them. According to Apuleius, Plato developed his own philosophical viewpoint after being introduced to the teachings of Heraclitus, studying with Socrates, encountering the Pythagoreans, and absorbing the dialectics of Parmenides and Zeno—the philosophical notions influencing Plato here being obviously those of the world as a continuous flux (Heraclitus), of the pursuit of universal definitions and of the primacy of the moral sphere (Socrates), of number as the underlying reality and of the immortality of the soul (the Pythagoreans), and of the contrast between real being and mere appearance (Parmenides).

Also according to Apuleius, Plato brought philosophy to perfection by combining the physics, ethics, and logic that had been pursued independently by the Pythagoreans, Socrates, and the Eleatics respectively into a single curriculum organized into three parts. On the basis of these historical data, one might therefore summarize the "essence of Platonism" as follows: Platonism is specifically characterized by the establishment of a contrast between the realm of being that is the object of knowledge or reasoning and is not subject to change and the realm of becoming that is the object of opinion or sensation and is liable to change. The two realms are linked by the soul, which exists indestructibly before, during, and after the temporal period of its combination with the body and for which assimilation either to the realm of being or to the realm of becoming represents the primary ethical choice.

Ancient Platonism

Modern scholars customarily divide Platonism in the ancient world into four main periods by using a mixture of ancient and modern terminology.

The "Old Academy" (347–267 BCE) is what Cicero called the original succession of philosophers within the Academy itself. The first of these philosophers was Speusippus (the scholarch, or "head of the school," 347–339 BCE), whose written works do not survive but whose doctrines can be reconstructed somewhat from later reports. Apparently Speusippus was influenced by the Pythagoreans into advocating as the first principles of reality, the One and the Dyad, the former transcending being, goodness, and intellect and the latter coinciding with matter. Speusippus abandoned Plato's own doctrine that the Forms were Ideal Numbers, yet emphasized Plato's teaching regarding the mathematicals intermediate between intelligibles and sensibles. He also explained the various levels of being as resulting from the relation between the One and different levels of matter.

Whereas Speusippus's theories were not influential until the time of the Neoplatonists, what became the standard type of Old Academic doctrine seems to have originated with his successor Xenocrates (scholarch, 339–314 BCE). Although the latter's works do not survive, it is possible on the basis of later reports to conclude that he produced the official edition of Plato's works and that he began a process of systematizing Platonic thought. For example, he established the formal tripartite division of philosophy into physics, ethics, and logic and he continued to develop the Pythagorean side of Plato's oral teaching. As first principles of reality, Xenocrates opposed the monad conceived as good to the dyad conceived as evil—the former corresponding to a self-thinking intellect containing the Forms or Ideal Numbers—and derived the entire cosmos from their interaction. The higher and lower worlds were mediated by a soul that was defined as a "self-moving number": in other words, it was self-moving like the soul of the Phaedrus and mathematically structured like that of the Timaeus.

Xenocrates' successor was Polemo (scholarch, 314–267 BCE), who seems to have differed from his two predecessors in that he placed somewhat greater emphasis on ethics. According to later testimonies, Polemo advocated the view that the goal of human existence was "life according to nature," this principle however required neither the rejection of external goods nor the extirpation of passions. Besides the three scholarchs, the Old Academy included other significant thinkers, including Crantor of Soli, the first known author of formal commentaries on the dialogues of Plato.

The New Academy (267–80 BCE) is distinguished by Cicero from the Old Academy on the basis of its shift from a dogmatic to a skeptical mode of philosophizing. Although this radical change of direction seems to have occurred in reaction to the extreme dogmatism of the current Stoic school, it appealed to the aporetic method illustrated by Socrates in the early dialogues of Plato for its historical justification. Arcesilaus (scholarch, 267–241 BCE), who followed the Socratic practice of writing nothing, argued that the degree of cognitive certitude claimed by the Stoic notions of perspicuity and assent was unattainable and that the correct epistemological attitude to the physical world was one of "withholding assent" (epochē ). In fact, Arcesilaus did not hold to the position that nothing could be known, but more radically to the viewpoint that one cannot be certain whether anything can be known or not.

Later thinkers in the New Academic tradition slightly modified Arcesilaus's teaching. Carneades (scholarch, c. 160–129 BCE) agreed that it would be possible to reject the Stoic notions of perspicuity and assent while being guided in practical matters by observing three levels of probability. The end of the New Academy seems to have been occasioned by a dispute, the precise details of which are somewhat obscure, between Philo of Larissa (c. 130–69 BCE) and Antiochus of Ascalon (160–80 BCE). According to one reading of the evidence, Philo attempted to reconcile the New Academy and the Old Academy, whereas Antiochus, who was particularly enraged by the interpretation gaining currency that Arcesilaus and Carneades had endorsed the skeptical position publicly while indulging in dogmatic activities in private, preferred to reestablish the Old Academy entirely.

Modern historians call the next phase of ancient Platonism (80 BCE–c. 250 CE) "Middle Platonism." This terminology has been established in order to characterize Platonism in the period between the revival of dogmatism in the Academy by Antiochus of Ascalon and the innovations of doctrine introduced by Plotinus. Although it is applied to a number of philosophers working at different times and in different places, it is perhaps possible to identify certain methods and doctrines as typical of this phase of the tradition. From the viewpoint of methods, the Middle Platonists concentrated on the dogmatic aspects of the tradition—although aporetic and dogmatic elements co-exist in the work of Plutarch of Chaeronea (c. 45–125 CE)—and within the dogmatic approach there is a strong tendency toward systematization. The practice becomes fully established of writing commentaries on Plato's work: Eudorus of Alexandria (fl. c. 25 BCE) is reported to have followed Crantor in commenting on the Timaeus —and also of producing handbooks of Platonic teachings—examples of this genre are extant in the form of the Didaskalikos of "Alcinous" (fl. c. 130 CE) and On Plato and his Doctrine by Apuleius of Madaura (b. c. 125 CE). The tendency toward systematization is accompanied by a tendency toward syncretism. From Aristotelianism, Plutarch can adopt the ethical doctrine of the mean and Alcinous the logical doctrine of the categories. The combination of Pythagoreanism and Platonism implicit in the assumption of monad and dyad as first principles continues with figures like Eudorus, this development being associated with the rise of Platonizing pseudo-Pythagorica around this time (for example, the treatises On the Soul of the Universe and On Nature by "Timaeus of Locri" and On the Nature of the Universe by Ocellus Lucanus).

From Stoicism, Antiochus of Ascalon can adopt the physical doctrine of active and passive principles and Atticus (fl. c. 170 CE) the ethical doctrine of extirpating passions. From the viewpoint of doctrines, the following physical ideas may be considered as particularly characteristic of Middle Platonism: (1) controversy over the corporeality or the incorporeality of the first principle—here the position of Antiochus should be contrasted very clearly with that of Eudorus and the rest of the tradition; and (2) postulation of a triadic group of first principles consisting of a first God that is One as in Pythagoreanism and Good as in the Republic and corresponds to a self-thinking Intellect containing the Forms; a second God having affinities with the Demiurge of the Timaeus and the Logos of Stoicism; and a World Soul sharing features with the principle of the same name in the Timaeus and the Indefinite Dyad of the Pythagoreans; and (3) tentative emergence of a first principle above Being itself in the work of Numenius of Apamea (fl. c. 150 CE). Among the ethical ideas characteristic of Middle Platonism might be mentioned the debate over the goal of human life. Here, the Antiochean notion of assimilation to nature should be contrasted with the Eudoran ideal of assimilation to God.

The phase in the history of Platonism initiated by the philosophy of Plotinus and in the twenty-first century called "Neoplatonism" may be divided into several "schools," in the sense of being associated with certain leading thinkers: namely, that of Plotinus and his students Porphyry and Amelius, that of Iamblichus and his followers, and the Athenian school from Plutarch of Athens, through Syrianus and Proclus, to Damascius. This last school claimed to be the successor of the ancient Academy and was closed by the Emperor Justinian in 529 CE.

Plotinus (204–269 CE) studied with Ammonius Saccas in Alexandria and later established his own school in Rome. He set out a metaphysical system, which, with various additions and modifications, became foundational for Platonic philosophy and for the reading of Plato until modern times. Thanks to the complete corpus of Plotinian writings called the Enneads and the biography attached by Porphyry to his edition of the latter, historians can understand the methods and doctrines of Plotinus more than they can those of any previous Platonist. The Enneads reveal precisely how Plato's works yielded systematic metaphysical tenets: The Republic provided the notion of the Good above Being; the Parmenides provided the postulation of the One, the One-Many, and the One-and-Many as the three first principles; the Symposium provided the identification of Beauty and Intellect; the Sophist provided the five Kinds constituting Intellect; the Phaedrus provided the relation between universal and individual Soul; the Phaedo provided the individual soul's attachment and detachment from the body and the notion of virtue as purification; the Theaetetus provided the notion of assimilation to the divine; and the Timaeus provided the distinction between being and becoming, the notion that the divine has no envy, the treatment of the intelligible living creature as a phase of Intellect, the treatment of the Demiurge as an intellective phase of Soul, the indivisible and divisible components of Soul, the cosmological reading of the lower gods, and the identification of the Receptacle and Matter.

Plotinus's philosophical approach was sometimes based on the interpretation of a specific passage, often quite brief, in Plato's dialogues, sometimes based on the discussion of a particular problem (e.g., that of the relation between Intellect and intelligible objects raised by Porphyry and recorded in Enneads V. 5), sometimes based on the critique of some false interpretation of Plato (e.g., that of the evil nature of the visible world maintained by the Gnostics and reported in Enneads II. 9) but usually based on a combination of the above. Porphyry's Life of Plotinus describes the role of sources other than Plato in these discussions, Aristotle's Metaphysics being particularly influential (a statement corroborated by Plotinus's use of the doctrines of potency and act and of the self-thinking intellect), both Platonic and Peripatetic commentators (e.g., Gaius and Alexander respectively) being sources of inspiration, and Stoic doctrines also being utilized (a statement corroborated by Plotinus's dematerialized reading of the pneuma as "procession and reversion").

The system emerging from this analysis might perhaps be summarized as follows. According to Plotinus, reality—understood dynamically as a descending hierarchy of "procession" (ontological founding and at certain points ethical fall) and as an ascending hierarchy of "reversion" (ontological completing and at certain points ethical perfecting)—consists of three principles or "hypostases": the One or Good (described less determinately as the Beyond, the Supreme, the First), which is cause or power; Intellect—a macrocosmic unity and microcosmic plurality that timelessly thinks itself is logically distinguishable into the five Platonic Kinds of Being, Sameness, Otherness, Motion, and Rest, and metaphysically contains the Platonic Forms; and Soul—a macrocosmic unity and microcosmic plurality that generates time and receives the Platonic Forms into itself as reason-principles. This hypostasis also contains a higher and a lower aspect: Soul proper and Nature. Below these three principles is the nonprinciple of Matter (in some but not all contexts called Evil), which receives the unfolding of Soul's lower aspect by projecting the Forms into three-dimensional space. The reversion is the more complex of the two dynamic aspects of reality given that it also comprises the epistemological transition from the discursive and propositional reasoning of Soul to the intuitive and nonpropositional thinking of Intellect to that which is approached in an entirely noncognitive manner.

Iamblichus (c. 245–325 CE) presided over an influential philosophical school at Apamea in Syria. He devoted himself to formal commentary on both Plato and Aristotle, a practice in which he followed his teacher Porphyry, and wrote an extensive study of Pythagorean mathematics. His approach to philosophy initiated certain tendencies especially characteristic of later Neoplatonism: namely, increasing emphasis on systematic and religious elements. In the former case, Iamblichus reinforced both the continuity and the discontinuity between the Plotinian hypostases by introducing numerous mediating terms; in the latter, he postulated a more radical fall of the human soul that could only be reversed by ritual observances. For Iamblichus, the systematic and religious aims came together since the discernment of more levels of reality provided a metaphysical foundation for traditional polytheism.

Proclus (412–485 CE) was the most influential representative of the Athenian school of Neoplatonism. In a number of extant works that include commentaries on Plato's Alcibiades, Cratylus, Parmenides, Republic, and Timaeus, a commentary on Euclid's Elements, and such independent treatises on Platonic philosophy as The Platonic Theology and the Elements of Theology, Proclus extended the emphasis on systematic and religious aspects of philosophy already detectable in Iamblichus. The systematization was particularly influential. This can be seen in his Commentary on the Parmenides, where he interpreted the famous dialectical discussion starting from the hypothetical proposition "If it is (there is a) one, the one will not be many" by applying the first five hypotheses to the One, the "ones" or gods together with the beings participating in them, nondivinized souls, Forms in Matter, and Matter; by associating three senses of "One" (above Being, with Being, and below Being) with the first three hypotheses; and by showing that all the attributes denied of the One in the first hypothesis are affirmed of the gods in the second.

Systematization can also be seen in the Elements of Theology where Proclus applied a method reminiscent of Euclidean geometry in order to "demonstrate" through a series of propositions, proofs, and corollaries and starting from certain initial propositions such as "All that is unified is other than the One itself" what philosophers must believe regarding the One itself (propositions 1–6), regarding the relation between the One and the other hypostases of the expanded post-Iamblichean order of being (propositions 7–112), and regarding the other hypostases themselves (propositions 113–211).

Medieval Platonism

The medieval Platonic tradition can be divided into the non-Latin and Latin traditions, the former in its turn being divisible into the Byzantine, Arabic, and Jewish traditions. But before turning to these, a few comments are necessary regarding certain transformations of ancient philosophy by patristic writers that formed a basis for later developments.

The most important intermediary between ancient and medieval Platonism in the West was Augustine of Hippo (354–430 CE). In the autobiographical Confessions, Augustine reported his encounter with "certain Platonic books translated from Greek into Latin" (Confessions VII. 9)—assumed to be writings of Plotinus and Porphyry by most scholars—and his consequent liberation from the dualistic and materialistic tenets of Manichaeism that had formerly impeded his progress toward Christian truth. What is being described here in narrative terms is the discovery of that synthesis of Platonism (specifically Neoplatonism) and Christianity that becomes a standard feature of Augustine's writing. This synthesis included two versions of a Platonic theory of first principles: (1) the identification of the Neoplatonic One and Being/Intellect with the Trinitarian Father and Word respectively (as in Confessions VII. 9); and (2) the identification of the One and Being/Intellect with God and the angels respectively (as in On the Literal Interpretation of Genesis II. 15ff.).

These two versions of Platonism are moving in opposite directions, since in the former case the universal aspect of the second principle is intensified while the hierarchical relation between the first and second principles is weakened; in the latter, the universal aspect of the second principle is weakened while the hierarchical relation between the first and second principles is intensified. The most important intermediary between ancient and medieval Platonism in the East was "Dionysius the Areopagite." This otherwise unknown fifth-century Christian achieved a posthumous authority by writing an important group of theological treatises, including On the Celestial Hierarchy, On Divine Names and On Mystical Theology, under the pseudonym of the first-century Dionysius famously converted by St. Paul.

On Divine Names in particular provides a skillful Christian adaptation of late pagan Neoplatonism in which the negative and affirmative predicates of hypotheses I and II of Plato's Parmenides are applied not to the One and the gods respectively—as in Proclus's commentary—but to a God or "Thearchy"—who is simultaneously transcendent of and immanent in created things. This important transformation in the direction of monotheism has as further philosophical consequences that the distinction between the transcendence and immanence of the deity by being partially mind-dependent introduces an element of idealism into the realist ontology characteristic of traditional Platonism. The Augustinian and Pseudo-Dionysian versions of the Neoplatonic theory of first principles should especially be compared with regard to their handling of the theory of Forms and the doctrine of Soul. With respect to the Forms, both writers understood Forms in the sense of physical paradigms as contained in the divine Intellect but Forms in the sense of moral absolutes as equivalent to divine attributes. With respect to the Soul, both authors removed the universal Soul from their system but, with suppression of the idea of transmigration between bodies, retained the function of individual souls.

The most important thinker within the Byzantine tradition of medieval Platonism is Michael Psellus (1018–1078). This author's claim to have revived the discipline of philosophy single-handedly is justified to the extent that, in an environment dominated by orthodox Christianity and methodological Aristotelianism, he reestablished the patristic notion of Platonism as a forerunner of Christianity and the later Neoplatonic notion of a relation between Aristotle and Plato in which the former's physics serves as an introduction to the latter's theology. Although Psellus is hardly responsible for metaphysical innovations in works like On Plato's Psychogony and On the Ideas Which Plato Mentions, the fact that he discussed philosophy by explicitly combining pagan Platonic sources such as Plato, Proclus, and Plotinus with Christian Platonic sources such as Gregory of Nyssa, Pseudo-Dionysius, and Maximus the Confessor represents an innovation in textual practice.

More specifically, this practice might be characterized as selective in that it isolates only certain aspects of traditional Platonism as compatible with Christianity—for example, by removing all theurgic elements (in On the Activity of Demons )—as allegorical in interpreting metaphysical principles in pagan texts as symbols of metaphysical principles in Christian scripture, and as combinatory in that it juxtaposes groups of notions drawn from traditional Platonism and Christianity without reducing the conflicting elements—for example, by combining Proclus's metaphysical interpretation of Jupiter's relation to the lower gods with the pseudo-Dionysius's of the Thearchy's relation to the angelic ranks (in On Homer's Golden Chain ). This highly original textual manipulation of Platonism established an intellectual tradition that endured until the fall of Constantinople. Later representatives include John Italos (c. 1025–after 1082), Eustratios of Nicaea (fl. at the end of the eleventh and early twelfth centuries)—author of a commentary on Aristotle's Nicomachean Ethics, which includes material from Proclus and was translated into Latin by Grosseteste, and Nicholas of Methone (mid-twelfth century), author of a "refutation" of Proclus's Elements of Theology.

That Arabic writers were able to make a major contribution to the development of medieval Platonism not only in the Islamic but also subsequently in the Christian world resulted from a fortunate circumstance: the availability of some reasonable translations as sources. Under the Umayyad and ʿAbbāsid caliphs, a vast enterprise of translating scientific and philosophical works from Greek into Arabic (sometimes through the intermediary of Syriac) was undertaken by such figures as Hunain b. Ishāq (808–873) and Qustā b. Lūqā (tenth century) with the result that all of Aristotle except the Politics, a certain amount of Plato, and many Greek philosophical commentaries, became available. It was in such a milieu that an important group of philosophical apocrypha arose.

This group consists of: (1) an Arabic "Plotinian" corpus (possibly the remains of a translation and commentary on Enneads IV–VI produced in the circle of al-Kindī [b. late eighth century and d. after 866]) comprising the Theology of Aristotle, the Letter on Divine Science, and the Sayings of a Greek Sage ; (2) the adaptation of Proclus's Elements of Theology, later known to the Latins as the Book of Causes (the Arabic original of which was produced before 992); and (3) an Arabic translation of approximately thirty-five propositions from Proclus's Elements of Theology and Elements of Physics. These works are connected through their expression of metaphysical teachings that depart from their Plotinian or Proclean originals in identical ways: namely, in describing the first principle as Pure Being—meaning Being without Form—rather than as the One above Being; and as creating, without any preexistent term or materiate substratum—rather than as causing—all subsequent principles. Moreover, that the first principle or Creative Being does not relate indirectly—through the mediation of an order of gods or "ones"—but directly to the second principle or Created Being is the common doctrine of the apocrypha.

During the next few generations, various writers developed a uniquely Arabic approach to the reading of the philosophical tradition in which a Neoplatonic doctrinal component drawn from sources of the type mentioned was inserted into an overtly Aristotelian context. Within this tradition al-Fārābī (Latin: Alfarabius [d. 950]) outlined a program of harmonizing Aristotelian and Platonic doctrine in his Reconciliation of the Two Sages, Philosophy of Plato, Philosophy of Aristotle, Attainment of Happiness, and Opinions of the Inhabitants of the Virtuous City. According to his metaphysical system, the Supreme Being or One produces a series of intellects, each of which can think its cause (thereby giving rise to a further intellect) and itself (thereby giving rise to a celestial sphere), this theory being understandable as the transfer of the emanative causal mechanism from the Neoplatonic hypostases to the Aristotelian unmoved movers.

Also within this tradition Ibn Sinā (Latin: Avicenna [980–1037]) organized knowledge into logic, physics, and metaphysics along Aristotelian lines in his encyclopedic Book of Healing and its abridgement the Book of Salvation. He further developed al-Fārābī's metaphysical system in proposing that, when the Supreme Being produces the subsequent terms, the first intellect in a threefold process first thinks the Being necessary in itself (thereby producing by emanation the second intellect), then itself as necessarily existing through its cause (thereby producing the soul of the first heaven), and finally itself as contingently existing through itself (thereby producing the body of the first heaven), this process being repeated until all the intellects, souls, and heavens have been generated. The inevitable reaction came when Ibn Rushd (Latin: Averroes [1126–1198]) attempted to liberate the authentic Aristotle from such Neoplatonizing tendencies. Of his two most famous interpretative innovations, the doctrines that the intellects are not connected by emanation and that there is a single agent and materiate intellect for all humanity, the first but not the second obviously runs counter to Neoplatonism. Ethical and political thought was not neglected by the Arabs and, since both Plato's Laws and Republic were available in Arabic, in this area they tended to be more Platonic than Aristotelian. Among examples of their work are al-Fārābī's compendium of the former dialogue and Ibn Rushd's commentary on the latter.

The most important thinker within the Jewish tradition of medieval Platonism is Solomon ben Judah ibn Gabirol (Latin: Avicebron [c. 1021–1058]). As the author of some excellent poetry in Hebrew, including the famous Kingly Crown and one philosophical treatise in Arabic, Ibn Gabirol stands within two cultural traditions. The philosophical work, which survives only in the Latin translation by Iohannes Hispanus and Domenicus Gundissalinus under the title of Fountain of Life, continues the speculative approach of the Arabic apocrypha but also develops the latter in an original style. Ibn Gabirol argued that the duality of form and matter underlies both the spiritual and the corporeal levels of reality, this combination of the formal and the material being used in subtle ways to explain the relation between unity and plurality. Although form and matter are also two closed doors between the human intellect and its Creator that are difficult to pass through, one can describe the Creator as Wisdom, Unity, and Will inasmuch as he is the cause of form and as Being inasmuch as he is the cause of matter.

Ibn Gabirol's duality of form and matter in created things represents the moments of determination and undetermined within an emanation, as indicated by his references elsewhere to the dynamic process whereby the inferior comes forth from and strives for union with the superior. Although a Hebrew translation of certain extracts was subsequently made by Ibn Falqera and there may have been some influence on the Jewish mystics of the Gerona circle, the philosophical afterlife of the Fountain of Life was mainly in the world of Latin scholasticism.

Because only the Timaeus was available in Latin (translated up to 53c with commentary by Calcidius [fourth century CE]) throughout the Middle Ages, the translations of the Meno and Phaedo (by Aristippus of Catania [d. 1166]) and of the Parmenides (included in Proclus's commentary up to 142a translated by William of Moerbeke [c. 1215–1286]) achieving only limited circulation towards the end of the period, one refers to a predominantly indirect transmission of doctrine in speaking of a "Platonic" tradition in the medieval Latin world. However, even this restricted definition of the latter is problematic given that the doctrines concerned are usually combined with Christianity and, during the thirteenth to fifteenth centuries especially, with Aristotelianism. One way of approaching the medieval Latin tradition of Platonism is perhaps to distinguish certain doctrinal clusters; that is, groups of philosophical teachings that exhibit sufficient coherence among themselves and predominate sufficiently in the context where they occur, and then to track the evolution of these clusters through medieval thought. The most important clusters are the following:

(1) A "Timaean" cluster. This group of doctrines, which is presented in passages of Augustine's Against the Academics, On the City of God, and On Eighty-Three Different Questions (qu. 46), based on Cicero's works (including his partial translation of the Timaeus ) and also in Calcidius's Commentary on the Timaeus and Macrobius's Commentary on the Dream of Scipio, represents a systematic and cosmological Platonism. It emphasizes the metaphysical principles of Soul and Nature, interprets the transcendent Forms as thoughts in the divine mind, and in general has affinities with the Middle Platonic doctrine of Antiochus of Ascalon.

(2) A psychological and Augustinian cluster. Based on Augustine's Soliloquies and On the Trinity, this group identifies the relations between the macrocosmic and microcosmic aspects of the Neoplatonic hypostases of the One and Intellect respectively along Porphyrian lines in order to ground human cognition or rather supracognition of the First Principle.

(3) A mathematical cluster. Based on the ancient tradition dating back to Xenocrates, it is transmitted to the Middle Ages by Boethius's On Arithmetic, On Music, and On the Consolation of Philosophy. This group emphasizes the relations between the monadic and dyadic aspects of the hypostases and between monad, dyad, and number series.

(4) A "Proclean" cluster. This group of doctrines, which is presented in different ways by Latin translations of the Pseudo-Dionysian corpus (by John Scottus Eriugena [d. c. 877–879] and several later writers), of the Arabic Book of Causes (by Gerard of Cremona between 1160 and 1187), and of Proclus's Elements of Physics (by an unknown translator c. 1160), Elements of Theology, Commentary on the Timaeus, Commentary on the Parmenides, and Minor Theological Tractates (all by William of Moerbeke between 1268 and 1286), represents a systematic and theological Platonism. It emphasizes the metaphysical principles of the One and Intellect, interprets the transcendent Forms as divine attributes or names, and in general is aligned with the Neoplatonic doctrines of the Athenian School.

(5) A psychological and Avicennian cluster. Based on the Latin translation of the psychological portions of Ibn Sīnā's Book of Healing (probably by Ibn Daud [d. c. 1180] and Dominicus Gundissalinus [fl. 1126–1150]), this group equates the relation between the macrocosmic and microcosmic aspects of the Neoplatonic hypostasis of Intellect with the conjunction between the separate agent intellect and the human intellect used by Arabic Aristotelianism to combine the abstraction of universals with the emanation of Forms.

In the medieval Latin world, these clusters occur in the following combinations and sequence. In John Scottus Eriugena's On Natures, cluster 4 as it occurs in the pseudo-Dionysian corpus is developed into a comprehensive metaphysical doctrine in which everything that is and is not can be divided on the one hand into the four quasi-species of "creating and not created," "creating and created," "not creating and created," and "not creating and not created" and on the other into a procession and a reversion of the First Cause with respect to its effects and of the effects with respect to their First Cause.

In philosophers of the twelfth century there was a tendency to combine clusters 1 and 3. For example, Adelard of Bath (fl. c. 1110–1125), who also translated the writings of Euclid from Arabic, elaborated within the context of cluster 1 a view of nature and of reason as theologically quasi-independent and also a theory of universals designed to harmonize the opinions of Plato and Aristotle; see his On the Same and the Different and Natural Questions. William of Conches (d. c. 1154), in his Glosses on Plato's Timaeus, Glosses on Macrobius, and Philosophy of the World, wrote extensively on an issue central to a naturalistic cosmology but problematic for Christian theology: namely the status and function of the Platonic world soul. Thierry of Chartres (fl. 1121–1148), who was described by contemporaries as the greatest Platonist of his era, elaborated within the contexts of cluster 1 and cluster 3 a metaphysics in which the interaction between God's unity and Matter produces the multiplicity of Forms equivalent to numbers, the Trinitarian nature of God also being expressible arithmetically as 1 x 1 = 1; see his Commentary on Boethius's On the Trinity and On the Works of the Six Days.

With the appearance of translations from Arabic into Latin and the rise of the medieval university after circa 1200, Platonism had to compete with Aristotelianism: a task that it accomplished most successfully within the sphere of what modern scholars term "Latin Avicennism." In the anonymous Book of Avicenna on the First and Second Causes and the Emanation of Being, cluster 2, cluster 4 as it occurs in the Pseudo-Dionysius and in the Book of Causes, and cluster 5 are combined to produce a metaphysical system in which the procession and reversion of effects with respect to the First Cause begins with the production of the first created intellect by Pure Being, and in which cognition takes place when the human soul ascends from the looking of reason to the vision of intellect and the tenth created intellect or agent intellect combines with the human intellect. This text represents a kind of standard late medieval Platonism to which all serious thinkers will have to react whether they are predominantly Aristotelian (e.g., Albert the Great [c. 1200–1280]) or predominantly Platonic (e.g., Dietrich of Freiberg [c. 1240–1318/1320], Meister Eckhart [c. 1260–1327]) in tendency.

Modern Platonism

The modern Platonic tradition can be divided into a phase beginning with the impact of the early-fifteenth-century humanist movement and a phase beginning with Friedrich Daniel Ernst Schleiermacher's German translation of Plato (published 1804–1809). The former phase might also be termed the "early modern" or "Renaissance" phase of Platonism.

Humanism can be defined as an ideal of liberal education based on the study of grammar, rhetoric, poetry, history, and moral philosophy especially through the recovery of authoritative texts in Greek and Latin, the term "humanism" itself corresponding to the studia humanitatis advocated by the Roman rhetorician and philosopher Cicero. Although the beginnings of the humanistic movement can be detected in Northern France during the early twelfth century, the main development is usually traced from Francesco Petrarca (in English, "Petrarch," 1304–1374).

Taking their cue from the latter's pointed praising of Plato in preference to Aristotle, Italian humanists together with their Byzantine associates produced during the next century and a half a series of Plato translations based on newly imported manuscripts. These included Latin versions of the Republic by Manuel Chrysoloras and Uberto Decembrio, by Pier Candido Decembrio, and by Antonio Cassarino, versions of the Phaedo, Gorgias, several Letters, Phaedrus (partial), Crito, Apology, Symposium (partial) by Leonardo Bruni, of the Axiochus by Cencio de' Rustici, of the Ion by Lorenzo Lippi, of the Crito, Axiochus, and Euthyphro by Rinuccio Aretino, of several Letters and the Euthyphro by Francesco Filelfo, and of the Charmides (partial) by Angelo Poliziano. From this list of titles, one may conclude that the "humanists" interest in Plato was primarily focused on the literary, ethical, and political aspects of Plato's work.

The first Platonic philosopher affected by humanism was Nicholas of Cusa (originally Niklaus Krebs, 1401–1464), a fact indicated by his commissioning of a Latin translation of the Parmenides by the Byzantine émigré George of Trebizond, the manuscript of which exists, together with his own marginal notes (Volaterranus 6201, f. 61r–86v), in the twenty-first century. Although Nicholas was not familiar with the complete Parmenides when he wrote his most celebrated philosophical work On Learned Ignorance (1440)—and probably not even with the part reproduced in Moerbeke's Latin translation of Proclus's commentary—the teaching of the dialogue fitted naturally into the philosophical system already developed for that work on the basis of medieval sources.

In summary, that system involves the threefold distinction of an "absolute maximum" (God), a "contracted maximum" (the Universe), and a simultaneously absolute and contracted maximum (Christ). With respect to the absolute maximum (and also to the relation between the three maxima), one can discern a Pythagorean and Trinitarian metaphysical structure comprising unity, equality, and connection, which is applied to a Dionysian structure based on the contrast of negative theology (indicating divine transcendence) and affirmative theology (indicating divine immanence) in order to produce an original Cusan metaphysical structure consisting of what surpasses opposites, opposites as such, and the "coincidence of opposites." Although this system has many affinities with doctrines advocated during the Middle Ages, it is innovative in emphasizing the subjectivity of the negative-affirmative theological antithesis (by transferring the teaching of pseudo-Dionysius's On Mystical Theology to the cosmological sphere), in its frequent recourse to mathematical images: for example, the maximum, infinity, the circles and triangles of geometry, and the concord of music, and in emphasizing the coincidence inherent in opposition (again adapting the teaching of On Mystical Theology to a cosmological use), the combination of the first and last points epitomizing the "learned ignorance," which provided Nicholas with his title.

Marsilio Ficino (1433–1499) is a truly seminal figure who established a pattern of interpreting Platonic philosophy that remained fundamental for the next three centuries. By the late 1450s Ficino had acquired a sufficient reputation as a Platonic thinker and as a Greek scholar to be requested by the Florentine ruler Cosimo de' Medici in 1462 to translate Plato's complete works into Latin from a newly acquired manuscript, this translation appearing in a first edition in 1484 and a second edition in 1491. In addition to this commission, Ficino translated the Hermetic corpus (under the title Pimander ), the Enneads of Plotinus (published in 1492), and various treatises by Porphyry, Iamblichus, Proclus, Synesius, and Michael Psellus for the first time, and also made a fresh translation of the pseudo-Dionysian corpus.

Historians rate him highly not only as an exegete of Plato and Platonism (on the basis of his translations and the commentaries published with the latter) but also as a constructive Platonic thinker (on the basis of his substantial independent treatise titled The Platonic Theology or On the Immortality of the Soul ). Ficino is important as an exegete because he considered for the first time since antiquity the complete writings of Plato and was therefore able to draw material from dialogues unavailable during the Middle Ages and to engage more fully with the argumentative context of Plato's teaching. Moreover, he proposed a special interpretation of the history of philosophy under the influence of late ancient and Byzantine writers and of Diogenes Laertius's Lives of the Philosophers according to which the Christian revelation beginning from Moses is confirmed by a unified and harmonious system of pagan theology emerging as a sixfold transmission linking Hermes Trismegistus with Orpheus, Aglaophemus, Pythagoras, Philolaus, and Plato.

Dionysius the Areopagite plays a pivotal role in this theory, which basically unifies disparate ideas through allegorical reading. As a thinker of unique inspiration and apostolic authority, Dionysius disclosed the truths concealed in the ancient system to pagan Platonists like Plotinus, the latter in turn transmitting those truths back to Christian writers such as Augustine. Ficino is important as a constructive thinker because he developed the Neoplatonism not only of Proclus (which had become known toward the end of the medieval period) but also of Plotinus (which was almost totally unknown during the Middle Ages) in directions more consistent with the Christian sense of human dignity and individuality. For example, the hypostatic system is sometimes recast so that Soul, instead of being simply the lowest of the three principles of the One, Intellect, and Soul, becomes the third member of a series of five terms God, Angel, Soul, Quality, and Body. This arrangement not only gives Soul a mediating and therefore sustaining function but supplies a novel argument for Soul's immortality in that if Soul were dissoluble then the entire order could likewise suffer dissolution. The hypostatic system is also sometimes modified in that Soul, instead of ascending or descending by identifying with the adjacent term of the series conceived dynamically in the upward direction, ascends or descends by passing through static regions formed by the adjacent terms on both sides.

One work by Ficino was particularly influential both inside and outside philosophy: namely, On Love written in 1469 and published in 1484. In fact, it is largely owing to this free commentary on Plato's Symposium that Platonism was to become among all doctrines in the history of philosophy the most influential on literature, the visual arts, and music.

Another Platonic philosopher affected by humanism was Giovanni Pico della Mirandola (1463–1494). In his Conclusiones —a set of 900 philosophical theses that he would have defended in a public disputation had the Pope not intervened by declaring some of them heretical—Pico attempted to extend the notion of a universal system underlying philosophy by adding the Jewish Kabbalah to the Egypto-Hellenic tradition described by Ficino. On the basis of the number of theses drawn from different schools of philosophy in the more historical first part of the work, it would seem that Proclus (supplying fifty-five theses) and the Kabbalists (supplying forty-seven theses) are the most important influences, the organization of the project itself into a set of propositions recalling Proclus's methodology (as in the Elements of Theology ) and the ascription of numbers to the propositions reflecting the Kabbalistic approach (900 being the numerical value of the cruciform Hebrew letter tsade ).

Other writings by Pico also respond to Ficinian ideas. The Oration (called Oration on the Dignity of Man after Pico's death) and the Heptaplus elaborate the notion of Soul as central in the order of reality, while On Being and Unity (part of a projected work On the Concord of Plato and Aristotle ) discusses the question whether among first principles Unity is prior to Being or not. In the latter essay, Pico's conclusion that Unity is not prior to Being according to either Plato or Aristotle required him to argue that hypothesis I of the Parmenides forms part of a purely dialectical exercise and thereby to sustain the Porphyrian, Arabic, and Latin rather than the Plotinian version of the Neoplatonic theory of first principles. In both these cases his theories deviate from Ficino's normal view.

The question of the impact of Platonism on the generations after Ficino is an extremely complex one. Despite the reading of Plato's dialogues in Greek courses at the traditional universities, the attempt of Francesco Patrizi (1529–1597) to establish courses on Platonic philosophy at the Universities of Ferrara and Rome, and the rise of numerous Platonically inclined literary "academies" in Italy and France, Platonism never displaced Aristotelianism institutionally. In fact, with respect to the sixteenth century it is necessary to speak of Platonic influence rather than of a Platonic tradition. Platonism during this period is partially a continuation of earlier tendencies. This description would apply to various discussions of Soul, for example when the Lateran Council of 1512–1517 proclaimed the immortality of the human soul as official dogma perhaps under the influence of Ficino, and when Giordano Bruno (1548–1600) incorporated the Plotinian theory of the World Soul into his cosmological speculation. Closely connected with the theory of Soul and disseminated by the various "academies" were the Platonic doctrines of spiritual love (derived from Ficino's reading of the Symposium ) and of divine madness (derived from Ficino's reading of the Phaedrus and Ion ) whose influence can be detected in Bruno's Eroici Furori and Patrizi's Della Poetica respectively.

Sixteenth-century Platonism is also partially an adaptation to newer ideas. Here, Platonism was rightly seen as having more in common with the rising mathematical sciences and quantitative thought than did Aristotelianism. Of the two main concepts of traditional mathematical Platonism, the notion of the a priori validity of numbers and of the symbolic power of numbers, Johann Kepler (1571–1630) applied both the first and the second and Galileo Galilei (1564–1642) the first but not the second to the astronomical-physical sphere.

With respect to the seventeenth and eighteenth centuries it is even more necessary to speak of Platonic influence rather than of a Platonic tradition. Platonism during this period is partially a continuation of earlier tendencies. This description applies to the philosophy of inner spirituality advocated by the "Cambridge Platonists" Henry More (1614–1687) and Ralph Cudworth (1617–1688), the last European thinkers to explicitly place themselves within the Platonic tradition. Seventeenth- and eighteenth-century Platonism is also partially an adaptation to newer ideas. Here, the notion of the intellectual love of God in Benedictus de Spinoza (1632–1677), the notion of reality as a system of spiritual monads each of which reflects the entire universe from its own viewpoint in Gottfried Wilhelm Leibniz (1646–1716), and the notion of thought reaching the sphere of things-in-themselves in the precritical thought of Immanuel Kant (1724–1804) are particularly important.

Between the sixteenth and eighteenth centuries there is also a remarkable example of a Platonism that might be considered as standing on the borderline between Platonic tradition and Platonic influence. The treatise Siris by George Berkeley (1685–1753) is a recommendation of tar-water as a panacea taking the form of a chain of reflections linking the properties of this liquid first with the chemical and physical phenomena of air and fire respectively and secondly with the spiritual world ascending to God. The main philosophical aims of Berkeley's study, which obviously blends the chain of reflections with the chain of being itself, are to oppose the mechanistic, materialist, and pluralistic view of the universe—well established by his own day—with a spiritual, immaterialist, and unified one, and also to supplement the sensuous immaterialism of his own earlier works—notably the Treatise concerning the Principles of Human Knowledge —with a theological idealism. The substantial final section of the treatise achieves its aims by mustering an impressive array of explicitly cited Platonic sources, including Plato's dialogues Alcibiades I, Phaedo, Republic, Theaetetus, Timaeus, Parmenides, and Letters, Plotinus's Enneads, Proclus's Platonic Theology, Bessarion, Ficino (especially his commentary on the Enneads ), Patrizi, and Cudworth.

On the basis of these authorities, it then argues that the three hypostases of Plotinian Neoplatonism are a reflection of the Christian Trinity. Here, the most important points to emerge are that Unity and Being are mutually convertible, that the placing of the hypostasis of the One before the hypostasis of Intellect or Being does not imply any atheism because there is nevertheless no time at which the One was without Intellect—an argument seemingly unprecedented within the Platonic tradition—and that the purely notional distinction between divine attributes allows the first point to be compatible with the second. The Platonic teachings quoted in Siris are clearly not to be taken too literally: Rather, the philosophical maxims of ancient times are proposed, as Berkeley put it, not as principles of logical demonstration but as hints to awaken and exercise the inquiring mind.

Schleiermacher's German translation of the writings of Plato (1804–1809), in which the necessity of distinguishing Plato's own doctrine from the teachings of later "Platonists" and the suggestion that the authentic teaching of the dialogues is superior to the pedantic systematizations of their later admirers was stressed, is rightly seen as the watershed in the history of Platonic interpretation. This new approach had already been gaining ground during the seventeenth and eighteenth centuries, as evidenced by various comments in Leibniz and reference books like J. J. Brucker's Historia Critica Philosophiae (1742–1744) and Denis Diderot's Encyclopédie (1751–1765). This approach underlines the change from the perception of a unified Platonic tradition to that of more fragmentary Platonic influences. But these changed circumstances present a new set of problems for any interpreter wishing to apply the term "Platonism" henceforth. In short, to what extent is it reasonable to speak of "Platonism" after 1800? A few comments on the "afterlife" of Platonism are perhaps in order.

One should begin by considering what might be termed modern historical studies on the question of "Platonism." Of relevance to the historical question are the distinctions intended by modern interpreters when employing the terms "Middle Platonism" (occasionally "Pre-Neoplatonism") and "Neoplatonism" with respect to the ancient tradition (see especially the works of Willy Theiler and Heinrich Dörrie). Although the application of such terminology assumes the principle of distinguishing between Plato's own doctrine and that of later exegetes, it does not exclude the possibility that a particular teaching originates with Plato himself, something that must be ascertained on a case by case basis. Also of relevance to the historical question is the notion that certain doctrines central to Plato's thought that were taught orally by the master but not included in his dialogues can be identified using the tools of modern criticism (see especially the works of Hans-Joachim Krämer and Konrad Gaiser). The study of such doctrines can yield clarification regarding both the meaning of certain teachings expressed obscurely in the dialogues and the origination of various doctrines associated with Middle or Neoplatonism.

These points represent historiography rather than philosophy in the wake of "Platonism." In order to identify a trajectory of modern philosophical Platonism, one might consider the following three cases in which influential doctrines have been or could be associated with Platonism:

(1) Georg Wilhelm Friedrich Hegel (1770–1831) in his Lectures on the History of Philosophy interpreted the Proclean triad of Being, Life, and Intellect within the intelligible world as corresponding to thought-determinations within the Hegelian Idea. One could tentatively propose this as a case of Platonism in that Hegel was explicitly reading a Platonic text and because his doctrine combines similarities with Platonism (the triadic structure occurs in Neoplatonism) with differences (the Platonic structure is abstractly universal whereas the Hegelian is concretely universal). But Hegel is obviously less a Platonist in either of the aforementioned senses than a creative reader of Platonism.

(2) Gottlob Frege (1848–1925) in his Foundations of Arithmetic postulated purely logical objects, which inhabit a logical realm of the objectively nonreal in contrast with the physical realm of the objectively real and the psychical realm of the subjectively real, and which especially include numbers. Scholars frequently describe his thinking as "logical Platonism" in that, although Frege was not explicitly reading a Platonic text, his doctrine combines similarities with Platonism (the establishment of an a priori element) with differences (the Platonic element is an essence whereas the Fregean is a proposition). But scholars label Frege a Platonist in an extremely loose sense, given that what is common to Platonism and Frege does not enter into any recognizably systematic structure of Platonism.

(3) Martin Heidegger (1889–1976) in his The Essence of Truth: On Plato's Cave Allegory and Theaetetus interpreted the Platonic Forms not as what is real as opposed to what is apparent but as the interplay of appearance and concealment. One could again tentatively propose this as a case of Platonism in that Heidegger was explicitly reading a Platonic text and because his doctrine combines similarities with Platonism (the dual structure occurs in Neoplatonism) with differences (the Platonic duality is metaphysical in character whereas the Heideggerian is phenomenological in character). But Heidegger is again less a Platonist in either of the senses distinguished previously than a creative reader of Platonism.

These ideas in Hegel, Frege, and Heidegger are undoubtedly among the more powerful philosophical thoughts since the 1800s. They reveal clearly that, although Platonism declined in significance as a tradition between 1600 and 1800, it has continued to provide a stimulus to philosophical activities of all kinds. There is no reason to think that this will not continue to be the case in the twenty-first century and beyond.

See also Agent Intellect; Alcinous; al-Fārābī; Ancient Scepticism; Antiochus of Ascalon; Arcesilaus; Augustine, St.; Averroes; Avicenna; Carneades; Cudworth, Ralph; Eckhart, Meister; Ficino, Marsilio; Frege, Gottlob; Hegel, Georg Wilhelm Friedrich; Heidegger, Martin; Ibn Gabirol, Solomon ben Judah; More, Henry; Neoplatonism; Nicholas of Cusa; Numenius of Apamea; Petrarch; Philo of Larissa; Pico Della Mirandola, Count Giovanni; Plato; Plotinus; Plutarch of Chaeronea; Porphyry; Proclus; Pseudo-Dionysius; Pythagoras and Pythagoreanism; Schleiermacher, Friedrich Daniel Ernst; Socrates.

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Stephen Gersh (2005)