The immediate philosophical background of Plotinus’s thought is of course the teaching of the Platonic school. Antiochus of Ascalon, who died about 68 B.C. and whose lectures Cicero heard at Athens, had revived positive philosophical teaching in Plato’s school, the Academy, after its sceptical and negative period. His own philosophy seems to have been a rather unsatisfactory sort of Stoic-Platonic eclecticism. But from this eclecticism there developed in the first two centuries A.D., with considerable influence from the revived studies of the mature works of Aristotle and the contemporary revival of Pythagoreanism, a new version of Platonism which in some ways anticipates Plotinus and has been of the very greatest importance for the later development of traditional European philosophy. The representatives of this Middle Platonism about whom we know anything are a very variegated collection. The best known is Plutarch, a thoroughly cultured and well-read man with wide interests and a very attractive personality, but not a profound or original thinker. Then there are serious but not very inspiring professional philosophers like Albinus, the sort of people who must have contributed most to the building up of Middle Platonism: and a fringe of third-rate transcen-dentalist speechifiers like Apuleius and Maximus of Tyre, who represent the popular pseudo-philosophy of the period in its most respectable form: for ideas derived from this new form of Platonism penetrated to still lower intellectual levels, into the secret revelations of Gnostics and Hermetists and right down to the magicians and alchemists. At the very beginning of the Christian era we find a remarkable attempt to interpret the Jewish Scriptures with the help of a not very consistent or coherent understanding of Greek philosophy, in which ideas of a Middle Platonist type predominate, in the works of Philo of Alexandria. The thought of the Neo-Pythagoreans, in so far as they were really philosophers and not just theosophists and magicians, is not easy to distinguish from that of the Platonists, and it seems best to regard both as forming part of a single group. Numenius, one of the most important of the immediate forerunners of Plotinus, can be called a Neo-Pythagorean, though it seems better to regard him as a Pythagoreanizing Platonist.
For our present purposes it will be enough to give a summary account of the main tendencies and characteristics of this philosophical movement without going into differences between individuals. Like the philosophy of Plotinus himself it is, as far as it is serious, a learned and bookish philosophy. Commentary on the works of Plato and Aristotle is beginning to become an important part of philosophical activity. Doxography, too, the collection and systematic arrangement of the opinions of the leading thinkers of all schools on the principal philosophical topics, plays a very important part in the philosophical development of the period. This learned activity brought with it a certain amount of eclecticism. The Platonists remained Platonists and not Aristotelians or Stoics; but they did sometimes study the opinions of thinkers of other schools with respect and in the hope of learning something from them. So we find in Middle Platonism a certain amount of Stoic influence and a much more important (at least from the point of view of the development of Neo-Platonism) admixture of Aristote-lianism.
The first principle of reality for the Middle Platonists is a transcendent Mind or God. The transcendence of this God is often very strongly stressed: the ‘negative theology’, the description of God by saying what He is not rather than what He is, so characteristic of Plotinus and of traditional theology ever since, begins to appear: and in some Neo-Pythagoreans we find anticipations of Plotinus’s doctrine of the One (NA: For a fuller discussion of Middle Platonist theology and its origins, cp. the first two chapters of my book The Architecture of the Intelligible Universe in the Philosophy of Plotinus (Cambridge, 1940): though much of what I say there about Plato needs drastic revision in the light of recent studies of the last phases of his thought.). This supreme Divine Mind is the place of the Platonic Forms or Ideas. Albinus speaks of them as’ thoughts of God’. This is a new development whose importance for the history of philosophy and theology need hardly be stressed. It ensured for the Platonic Ideas the place in traditional Christian thinking which they have never lost. Plotinus’s own doctrine is, as we shall see, rather different from but clearly dependent on the Middle Platonist. Below the supreme Mind in the Middle Platonists there is sometimes to be found a Second Mind or God, with a world-moving or world-ordering function, and below that again the Soul of the World. In the more popular versions of Middle Platonism the daemones, beings intermediary between gods and men who appear in Greek belief as early as Hesiod, play an important part. The idea of a hierarchy of spiritual powers between the supreme God and our world is always apparent. About matter and the origin of Evil the Middle Platonists disagreed; but they inclined to a dualist solution of the problem of evil, whether they saw its origin in an evil soul (Plutarch) or in matter itself (Numenius).
This very summary and sketchy account should be enough to show that the philosophy of Plotinus is in all essentials a development (though sometimes a very bold and original one) of the Middle Platonist school tradition. But there is another philosophical influence on his thought which must not be neglected. Plotinus devotes a great deal of time and energy in his writings to dealing faithfully with Stoicism, and in particular with the curious Stoic way of thinking of spiritual being in terms of body. It was probably the struggle to free his own mind and the minds of his pupils from the very pervasive influence of the Stoic conception of God and the soul as a sort of gas that led Plotinus to the very clear understanding of the difference between spiritual and material being which is such a valuable feature of his thought. But he does none the less show evidence of the influence of Stoicism, to a greater degree than his Middle Platonist predecessors and on some very important aspects of his thought. One of the things which must strike any reader of Plotinus very forcibly, especially if he comes to him from Plato, is his emphasis on life. Plato seems to have imagined the spiritual world as a place of static, regular mathematical pattern and geometrical intelligence ordering all things on that pattern. Plotinus’s spiritual world is a place ‘boiling with life’, where infinite power wells up and surges eternally in a carefree spontaneity without plan or need into a splendid superabundance of living forms. And both spiritual and material worlds are for him in their very different ways organisms, unities-in-diversity held together in a living whole by a single life. The liberation from Stoic corporeal ways of thinking enables Plotinus to give his own original developments to this sense of life. But it is impossible not to see that it owes a very great deal to the dynamic vitalism of the Stoics, who saw the universe as a single living organism held together, enlivened, and ensouled by the Divine Fire which was the fullness both of life and intelligence.
Plotinus of course, like his Platonist predecessors, considered his philosophy not, as modern historians of philosophy consider it, as a philosophy inspired by Plato and historically derived from Plato, but with a great many new and distinctive features which are certainly not to be found in Plato’s own thought, but simply as an exposition of Plato’s own system. It is quite clear from his writings that he thought that Plato had a systematic philosophy, that the answers to all important philosophical questions were to be found in the Dialogues if only they were interpreted rightly, and that the duty of a Platonist philosopher was simply to find and proclaim the right interpretations. But in fact the greatest difference between Plato and the Middle Platonist and Neo-Platonist philosophers is just that Plato is not a systematic thinker. It does not seem possible to maintain that there lies behind even the later Dialogues the sort of fully worked-out system of thought which lies behind the Enneads. Plato’s mind did not work like that. And we find that Plotinus arrives at his conception of Plato’s system by taking a rather limited number of passages from the later Dialogues out of their contexts, bringing them, sometimes with a good deal of forcing, into relation with each other, and interpreting them often in a very arbitrary way without reference to the sequence of thought in the dialogue in which they occur. This procedure and many of the interpretations (notably that of the second part of the Parmenides) seem to have been traditional in the Platonic school [NA: For a full discussion of the way in which Plotinus interprets Plato, see Schwyzer, art. cit., col. 550-553.]. This complete difference in kind between the two philosophies makes any detailed comparison between the system of Plato and the system of Plotinus impossible, because any such comparison must begin by making the untrue assumption that there is a system of Plato. But this does not of course mean that the two have nothing to do with each other, or that the observation of the similarities and differences between the minds of the two great philosophers is not of the most fascinating interest. Only a few brief indications, which interested readers can pursue further for themselves, can be given here, for the topic is an enormous one. We can say that Plotinus is genuinely in accord with Plato in his sharp division of reality into an eternal, spiritual or intelligible, and a temporal, material and sensible world, with the scheme of values and the view of human life which this division implies; and also in his conviction that the material world of the senses is good and ordered by divine intelligence and has its own sort of reality and importance in the scheme of things, and that though it is not the true home of the soul, yet the soul has its work to do in it. His view of the nature and destiny of the human soul is therefore in essence genuinely Platonic, except (and it is an important exception) in his doctrine of the final mystical union. His doctrine of a transcendent Principle of the World of Ideas and his sharp distinction between Nous and Soul, though they are not Platonic in their developed form, do seem to be genuine developments of ideas which are already to be found in Plato. But the placing of the Ideas in the Divine Mind, the emphasis on life and the organic view of reality, the doctrine that there are Ideas of individuals, and the doctrine of the Divine Infinity, all seem to belong to ways of thinking quite different from Plato’s and to have come to Plotinus from other sources, and their appearance in his thought means a radical transformation of Platonism.
Plotinus’s attitude to Aristotle, from whose philosophy, especially his metaphysics and psychology, he derives very much, is a good deal more independent and critical than his attitude to Plato. There was a strongly anti-Aristotelian group among the Middle Platonists, and Plotinus is obviously aware of, and sometimes accepts, their views. He knows that Aristotle often differs from Plato, and where he differs he is quite sure that he is wrong. On the whole, as a result of this greater detachment, we can say that he has a much more accurate understanding of Aristotle’s real thought than he has of Plato’s. There were historical reasons for this, too. The Peripatetic writers, the great commentator Alexander and others, who were read in his school, kept much closer to the real thought of Aristotle than the Middle Platonists did to that of Plato. Aristotelianism, after the publication of the great edition of Aristotle’s works by Andronicus in the ist century b.c. and until its final absorption by Neo-Platonism, was a matter of close commentary on the works of the master without much development of his thought, not a growing and changing philosophy like Platonism: a difference which is at least in part due to the difference between the clear-cut systematic philosophy of Aristotle and the thoroughly unsystematic and infinitely suggestive thought of Plato, which seems to stimulate his readers in every generation to find or make Platonic systems of their own (which they generally attribute to Plato himself).
The most important, but unfortunately probably unanswerable, question to ask about Plotinus’s philosophical background is, What was the content of the teaching of Ammonius Saccas, the philosopher who undoubtedly influenced him more than any other ancient or contemporary thinker? We have very little information about the teaching of Ammonius [NA: There are three passages which refer to his teaching, two in Nemesius, On The Nature of Man, 2. 29 and 3. 56, and one from the 5th-century Platonist Hierocles, quoted by Photius, Bibliotheca, cod. 251, p. 4610, 31 ff. and in a rather fuller form cod. 214, p. 172a, For a discussion of this evidence see Schwyzer, art. cit., col. 477-481.], who wrote nothing, and it is by no means certain how far one of the passages on which any attempt to reconstruct parts of his thought must be based (the quotation from Hiérocles) really refers to him at all. He seems to have taught, like other Middle Platonists, that Plato and Aristotle were in fundamental agreement. Nemesius attributes to him views about the nature of the soul and its relationship to the body which correspond exactly to the teaching of Plotinus. And it is possible that he taught the doctrine which we find in Hiérocles of a single supreme God who made the universe, a twofold hierarchically ordered unity of intelligible and sensible worlds, out of nothing. If this is really so, it would mean, first that Ammonius’s thought was still powerfully influenced by his Christian upbringing, in spite of his abandonment of Christianity, for creation out of no pre-existing matter is Judaeo-Christian, not Greek philosophical doctrine. This would help to account for the striking parallels between Plotinus’s language and Christian ways of speaking about God which have impressed his Christian readers since St. Augustine. It would also mean that the distinction between the One and Nous, which is one of the most important things in the philosophy of Plotinus, did not go back to Ammonius but was original (there is some evidence that the pagan Origen, another pupil of Ammonius, did not believe in it). But on the whole it is perhaps safer to say simply that we know almost nothing about the teaching of Ammonius, and therefore cannot be sure how far Plotinus simply reproduced or developed, or departed from, the teaching of his master. [NA: Longinus, who had heard Ammonius, certainly considered Plotinus to be an original thinker, cp. the long quotation in Porphyry, Life, ch. 20.]
The philosophy of Plotinus is, more even than other philosophies of the first centuries of the Christian era, not only a philosophy but a religion, a way for the mind to ascend to God. It is therefore worth while saying something about its relation to the non-philosophical religions of the time, those at least which aroused any genuine personal devotion. The official public cults meant little to Plotinus, though he makes, like other late Greek philosophers, a good deal of use of allegorical interpretations of the traditional myths for his own purposes. The mystery-religions cannot have contributed any ideas to his religious thought because they had no ideas to contribute. They were religions of cult and emotion, and, in so far as their more thoughtful devotees had anything approaching a theology, it was derived from the more easily understandable forms of contemporary philosophy and not from any sort of independent doctrinal tradition. All that Plotinus took from them was a certain amount of decorative symbolism (the language of light applied to spiritual being which plays so great a part in the Enneads does not derive specifically from mystery-rituals of illumination. Light-symbolism and the belief in a close connexion between light and divinity is a universal feature of all the religions and religious philosophies of the period). There is no evidence that Plotinus had any direct contact with orthodox Christianity, though Porphyry knew a good deal about it and attacked it vigorously. We can assume that Plotinus knew little about it, and that what he knew he disliked. Any direct and consciously recognized influence of Jewish or Christian ideas on his mind can be ruled out, and though we cannot absolutely exclude the possibility of indirect influence, perhaps through Ammonius or other contacts at Alexandria, we certainly cannot prove that such influence existed. And the fact that orthodox Christians, from St. Augustine and the Cappadocian Fathers to our own times, have been able to find a very great deal in Plotinus that has been of value to them should not prevent us from realizing that his system as it stands is in many ways incompatible with Christianity and belongs to a different type of religious thought.
Plotinus has left us in no doubt about his own opinions on the strange and powerful contemporary religious movement which we know as Gnosticism. He attacks it vigorously in the ninth treatise of the Second Ennead as untraditional, departing from the true teaching of Plato, irrational and inconsistent, insanely arrogant, and immoral in its tendencies. The neurotic Gnostic search for a secret sacred knowledge, a gnosis, the possession of which would automatically bring salvation, which led to the production and circulation of a mass of fantastic compilations claiming to be divine revelations and repositories of ancient Oriental wisdom, was utterly repugnant to his intelligent Hellenic conservatism, for which the philosophy of Plato was manifestly reasonable and taught the truth and showed the way to God to those who were able and willing to follow it by the exercise of intelligence and virtue. [NA: cp. Porphyry, Life, ch. 16, for the campaign of Plotinus and his disciples to expose the pseudonymous revelations of the Gnostics.] And his attitude to the visible universe was utterly opposed to that of the Gnostics. For them it was an evil prison, vitiated in its very nature, produced as the result of the fall of a spiritual power, with which man (or at least the Gnostic) who had come into it from a higher world as a result of that fall had absolutely nothing in common, which he utterly rejected and sought to escape from by means of the gnosis. For Plotinus, in this entirely true to Plato’s doctrine, the visible universe was good, an essential part of the nature of things, not the result of any fall or error but of the spontaneous expansion of the divine goodness to fill all possible being, made by divine intelligence as the best possible material image of the spiritual universe. Man was akin to and should venerate as nobler than himself the divine souls which moved the stars (in Gnostic belief evil or inferior, hostile powers) and the great Soul of the World. He certainly belonged by right to the spiritual world and should seek to return there and transcend the material even while in the body: but he should do it without resentment or impatience or denial of the goodness of the visible world and his own real duties there. On the other hand, Plotinus’s doctrine of matter (‘ prime’ matter, absolute formlessness, as distinct from body, which is formed matter and good in so far as formed) as ‘darkness’ and the principle of evil is in language and thought very like Gnosticism. And there are a good many other similarities of language and thought which a reading either of the Hermetic treatises, which represent a Gnosticism unaffected by Christianity, or of the accounts of the teaching of the Christianized Gnostics, will show [NA: There are some very striking ones in St. Irenaeus’s account of the teaching of Valentinus, Adv. Haer, I. i. i-I. 8. 4.]. The themes, for instance, of the transcendence and incomprehensibility of the Supreme Being Who is higher than Mind, and of the unity-in-diversity of the spiritual world recur in the Gnostic writings (many of which are earlier than, or contemporary with, Plotinus). These similarities, however, are not to be accounted for by supposing that Plotinus borrowed from the Gnostics. Ideas of this sort were ‘in the air’ and might appear in very different contexts and with endless adaptations and modifications in the thought of thinkers of very different schools.
We may sum up the general philosophical and religious situation in the age of Plotinus in the words of G. Quispel (Gnosis als Welt-Religion, ch. 3, p. 26.), ‘ Late antiquity appears to our mind’s eye as a land of three rivers, traversed by canals and with bridges which make traffic possible; but all the same three great streams appear distinctly, Gnosis, Neo-Platonism, and Christianity.’ There are innumerable interconnexions, but the three streams remain distinct, springing from different sources and flowing in different directions. And even when Christianity, after drawing into its stream a great deal of water from the other two rivers, flows on by itself, the result is not a mere syncretism or fusion. Christianity assimilates what it takes from the other two but remains itself.