As far as is known, the originator of this distinctive kind of Platonism was Plotinus (205–270 ce). He had been the pupil at Alexandria of a self-taught philosopher called Ammonius, who also taught the Christian Origen and the latter’s pagan namesake, and whose influence on his pupils seems to have been deep and lasting. But Ammonius wrote nothing; there are few reports of his views, and these are unreliable so that nothing is actually known about his thought. A number of distinguished scholars have made attempts to reconstruct it, but their speculations go far beyond the evidence. Plotinus must thus be regarded as the first Neoplatonist, and his collected works, the Enneads (from the Greek enneas, “set of nine”—six sets of nine treatises each, arranged by his disciple Porphyry), are the first and greatest collection of Neoplatonic writings.

Plotinus, like most ancient philosophers from Socrates on, was a religious and moral teacher as well as a professional philosopher engaged in the critical interpretation of a long and complicated school tradition. He was an acute critic and arguer, with an exceptional degree of intellectual honesty for his, or any, period; philosophy for him was not only a matter of abstract speculation but also a way of life in which, through an exacting intellectual and moral self-discipline and purification, those who are capable of the ascent can return to the source from which they came. His written works explain how from the eternal creative act—at once spontaneous and necessary—of that transcendent source, the One, or Good, proceeds the world of living reality, constituted by repeated double movements of outgoing and return in contemplation; and this account, showing the way for the human self—which can experience and be active on every level of being—to return to the One, is at the same time an exhortation to follow that way.

Plotinus always insisted that the One, or Good, is beyond the reach of thought or language; what he said about this supreme principle was intended only to point the mind along the way to it, not to describe or define it. But though no adequate concept or definition of the Good is possible, it was, nonetheless, for Plotinus a positive reality of superabundant excellence. Plotinus often spoke of it in extremely negative language, but his object in doing so was to stress the inadequacy of all human ways of thinking and speaking to express this supreme reality or to clarify the implications of the claim that the Good is absolutely one and undetermined, the source of all defined and limited realities.

The original creative or expressive act of the One is the first great derived reality, nous (which can be only rather inadequately translated as “Intellect” or “Spirit”); from this again comes Soul, which forms, orders, and maintains in being the material universe. It must be remembered that, to Plotinus, the whole process of generation is timeless; Nous and Soul are eternal, while time is the life of Soul as active in the physical world, and there never was a time when the material universe did not exist. The “levels of being,” then, though distinct, are not separate but are all intimately present everywhere and in everyone. To ascend from Soul through Intellect to the One is not to travel in space but to awake to a new kind of awareness.

Intellect for Plotinus is at one and the same time thinker, thought, and object of thought; it is a mind that is perfectly one with its object. As object, it is the world of forms, the totality of real being in the Platonic sense. These forms, being one with Intellect and therefore with each other, are not merely objects but are living, thinking subjects, each not only itself but, in its contemplation, the whole. They are the archetypes and causes of the necessarily imperfect realities on lower levels, souls and the patterns or structures that make bodies what they are. Humans at their highest are intellects, or souls perfectly conformed to Intellect; they become aware of their intellectual nature when, passing not only beyond sense perception but beyond the discursive reasoning characteristic of the life of Soul, they immediately grasp eternal realities.

Soul for Plotinus is very much what it was for Plato, the intermediary between the worlds of Intellect and Sense and the representative of the former in the latter. It is produced by Intellect, as Intellect is by the One, by a double movement of outgoing and return in contemplation, but the relationship between the two is more intimate and the frontier less clearly defined. For Plotinus, as for Plato, the characteristic of the life of the Soul is movement, which is the cause of all other movements. The life of the Soul in this movement is time, and on it all physical movement depends. Soul both forms and rules the material universe from above; and in its lower, immanent phase, which Plotinus often calls nature, it acts as an indwelling principle of life and growth and produces the lowest forms, those of bodies. Below these lies the darkness of matter, the final absence of being, the absolute limit at which the expansion of the universe—from the One through diminishing degrees of reality and increasing degrees of multiplicity—comes to an end. Because of its utter negativity, such matter is for Plotinus the principle of evil; and although he does not really believe it to be an independent principle forming, with the Good, a dualism, his language about it often has a strongly dualistic flavour.

He was not, however, really dualistic in his attitude toward the material universe. He strongly maintained its goodness and beauty as the best possible work of Soul. It is a living organic whole, and its wholeness is the best possible (though very imperfect) reflection on the space-time level of the living unity in diversity of the world of forms in Intellect. It is held together in every part by a universal sympathy and harmony. In this harmony external evil and suffering take their place as necessary elements in the great pattern, the great dance of the universe. Evil and suffering can affect humans’ lower selves but can only exceptionally, in the thoroughly depraved, touch their true, higher selves and so cannot interfere with the real well-being of the philosopher.

As souls within bodies, humans can exist on any level of the soul’s experience and activity. (The descent of souls into bodies is for Plotinus—who had some difficulty in reconciling Plato’s various statements on this point—both a fall and a necessary compliance with universal law.) Humans can ascend through their own intellect to the level of universal Soul, become that whole that they already are potentially, and, in Soul, attain to Intellect itself; or they can isolate themselves on the lower level, shutting themselves up in the experiences, desires, and concerns of their lower nature. Philosophical conversion—the beginning of the ascent to the One—consists precisely in turning away, by a tremendous intellectual and moral effort, from the life of the body, dominating and rising above its desires, and “waking to another way of seeing, which everyone has but few use.” This, Plotinus insisted, is possible while one is still in an earthly body and without neglecting the duties of one’s embodied state. But the body and bodily life weight the individual down and hamper him in his ascent. Plotinus’s language when speaking of the body and the senses in this context is strongly dualistic and otherworldly. Platonists in general think much more dualistically about their own bodies than about the material universe as a whole. The physical world is seen positively as a noble image of the intelligible; the individual, earthly, animal body, on the contrary, tends to be regarded negatively as a hindrance to the intellectual and spiritual life.

When an individual’s philosophical conversion is complete and he has become Intellect, he can rise to that mystical union in which the One manifests his continual presence, carried on the surging current of the impulse of return to the source (in its strongest and final flow), the pure love of Intellect for the Good from which it immediately springs. There is no consciousness of duality in that union; the individual is not aware of himself; but neither is he destroyed or dissolved into the One—because even in the union he is still Intellect, though Intellect “out of itself,” transcending its normal nature and activity. This mystical union for Plotinus was the focus of much of his effort and, for those of similar inclination, the source of the continuing power of his teaching. Philosophy for him was religion, the effort to actualize in oneself the great impulse of return to the Good, which constitutes reality on all its levels; and religion for him was philosophy. There was no room in his thought and practice for special revelation, grace, and repentance in the Christian sense, and little for external rites or ceremonies. For him the combination of moral purification and intellectual enlightenment, which only Platonic philosophy as he understood it could give, was the only way to union with the Good.