Plotinus
(304-270 A.D.)

Plotinus on the topic of evil:

Escape from Evil
Since evil is here, "haunting this world by necessay law," [Theatetus 176a] and it is the soul's design to escape from evil, we must escape hence. But what is this escape? "In attaining likeness to God," we read [Phaedo 82b]. And this is explained as "becoming just and holy, living by wisdom," the entire nature grounded in virtue. What could be more fitting than that we, living in this world, should become like to its ruler, to the Being in whom, above all, such excellence seems to inhere, that is, to the Soul of the cosmos and to the Principle ruling within it, the Principle endowed with a wisdom most wonderful?
    It is from the Supreme that we derive order, distribution and harmony, those virtues which are a principle of symmetry and beauty in us as long as we remain here; they ennoble us by setting bound and measure to our desires and sensibility, and dispelling false opinion, and this by sheer efficacy of the better, by the fact that the measured is lifted outside of the sphere of the unmeasured and lawless.
— The Enneads, I.ii.1 (p. 22)

The Nature and Source of Evil
Let us define the nature of the Good as far as our immediate purpose demands. The Good is that on which all depends, towards which all existences aspire as to their source and need, while Itself is without need, the measure and term of all, giving out from Itself Divine Mind and Being and Soul and Life and all intellective act.
    The Good is beyond beautiful, beyond the Highest, holding kingly state in that Intellectual Cosmos of which the Principle is wholly unlike what is known as intelligence in us. Our intelligence works by reasonings, examines links of demonstration, and comes to know the world of Being also by the steps of logical process, having no prior grasp of Reality, but remaining empty, all intelligence though it be, until it has put itself to school.
    But the Divine Mind is not of such a kind. It possesses all, It is all. It has all by other means than having, for what It possesses is still Itself. And the First Act is the Act of Good stationary within Itself; but there is also an Act directed towards It, that of the Divine Mind which, as it were lives about It. And Soul circles around Divine Mind and by gazing upon It, seeing into the depths of It, through It sees God. Such is the untroubled, blissful life of divine Beings, and evil has no place in it.
    If evil exist at all, it must be situate in the realm of non-being. By this non-being we are not to understand something that simply does not exist, but only something of an utterly different order from Authentic Being. Some conception of it would be reached by thinking of measurelessness as opposed to measure, the unshaped against a shaping principle, the ever-needy against the self-sufficing; while whatever participates in in and resembles it becomes evil, though not to the point of being evil absolute.
— The Enneads, I.viii.2-3 (pp. 54-55)

What then is the evil soul?
It is the soul that accepts unmeasure, excess and shortcoming which bring forth licentiousness, cowardice and all other flaws of the soul, all the states, foreigh to the true nature, which set up false judgments, so that the soul comes to name evil or good those things which it respectively flees or pursues (rather than to test them by their true value). Such a soul is not purely itself; it is shut out from the Forming Idea that orders and brings to measure, and this because it is merged in a body made of matter.
    Then if the reasoning faculty too has taken hurt, the soul's seeing is balked by the passions and by the darkening that matter brings to it, by its attention no longer to essence but to process whose principle or source is matter. Wholly without part in Good, the negation of Good, unmingled lack, this matter-kind makes over to its own likeness whatsoever comes in touch with it.
    But the soul wrought to perfection, addressed towards Divine Mind, is steadfastly pure; it has turned away from matter; all that is undetermined, that is outside of measure, that is evil, it neither sees nor draws near; it endures in its purity wholly determined by Divine Mind.
— The Enneads, I.viii.4 (pp. 55-56)

How do we explain the teaching [Plato's Theatetus 176a] that evils can never pass away but exist of necessity; that while evil has no place in the divine order, it haunts mortal nature and this place for ever? Does this mean that heaven is clear of evil, ever moving its orderly way, spinning on the appointed path, no injustice there nor any flaw, no wrong done by any power to any other, while injustice and disorder prevail on earth?
Not quite so; for the precept to "flee hence" does not refer to earth and earthly life. The flight consists not in quitting earth but in living our earth-life with justice and piety in the light of philosophy; it is vice we are to flee. The escape is not a matter of place, but of acquiring virtue, of disengaging the self from the body; this is the escape from matter. The soul's "separate place" is simply its not being in matter, not being united with it, not moulded in matter as in a matrix. This is the soul's apartness.
    Given that the Good is not the only existent thing, it is inevitable that by the outgoing from It, the continuous down-going from It, there should be produced a last; this will be evil. This last, the thing which has no residue of Good in it, is matter.
    Matter becomes mistress of what is manifested through it; it corrupts and destroys the incomer, it substitutes its own opposite character and kind by setting its excess and defect against the duly ordered. Thus what enters into matter ceases to belong to itself, comes to belong to matter, just as in the nourishment of living beings what is taken in does not remain as it came, but is turned into blood and becomes in fact any of the humors of the recipient. If, then, body is the cause of evil, there is no escape; the cause of evil is matter.
— The Enneads, I.viii.6-8, 11 (pp. 56-57)

But how may we know good and evil?
Virtue we may know by Divine Mind and by means of the philosophic habit; but vice? As a ruler marks off straight from crooked, so vice is known by its divergence from the line of virtue. Virtue is not the absolute Good and Beauty, because wwe know that these are earlier than virtue and transcend it, and that it is good and beautiful by some participation in them. Now as going upward from virtue we come to the Beautiful and Good, so, going downward from vice, we reach essential evil. We are become dwellers in the place of unlikeness, where, fallen from all our resemblance to the Divine, we lie in gloom and mud; for if the soul abandons itself unreservedly to the extremes of viciousness, as far as soul can die it is dead. This is our "going down to Hades and slumbering there." [Republic 534d]
    The vicious soul is unstable, swept along from every ill to every other, quickly stirred by appetites, headlong to anger, as hasty to compromises, yielding at once to obscure imagination; as weak, in fact, as the weakest thing made by man or nature, blown about by every breeze and eddy.
    But the faculties of the soul are many, and it has its beginning, its intermediate phases, its uttermost border. Matter importunes, raises disorders, seeks to force its way within; but all the ground is holy, nothing there without part in Soul. Matter therefore submits, and takes light; but the source of its illumination it cannot attain to, for the soul cannot endure this foreign thing. On the contrary the illumination streaming from the soul is dulled as it mixes with matter.
    This is the fall of the soul, this entry into matter; thence its weakness; not all the faculties of its being retain free play, for matter hinders their manifestation; it encroaches upon the soul's territory and, as it were, crushes the soul back and turns to evil what it has stolen until that finds strength to rise again.
    Thus the cause of the weakness of soul and of all its evil is matter. What soul could contain evil unless by contact with the lower kind? There could be no desire, no sorrow, no rage, no fear; fear touches the compounded dreading its dissolution; desires spring from something troubling the grouped being or are a provision against trouble threatened; the soul takes up false notions through having gone outside of its own truth by ceasing to be pure itself. The appetite or desire for the Divine Mind is something wholly other; with That, then, must the soul unite, dwelling alone enshrined in That, never lapsing towards the less.
— The Enneads, I.viii.9-10, 12 (pp. 57-58)

Providence and Evil
Thus we come to our enquiry as to the degree of excellence found in things of this Sphere, and how far they belong to an ordered system or in what degree they are, at least, not evil. But humanity, in reality, is poised midway between gods and beasts, and inclines now to the one order, now to the other; some men grow like to the divine, others to the brute, the greater number stand neutral. Those that are corrupted to the point of approximating to irrational animals pull the midfolk about and inflict wrong upon them; the victims are better than the wrong-doers, but are at the mercy of their inferiors in the field in which they themselves are inferior; in laziness and luxury and listlessness, they have allowed themselves to fall, like fat-loaded sheep, a prey to wolves.
    But the evil-doers also have their punishment; first they pay in that very wolfishness, in the disaster to their human quality [Laws 728b]; then, living ill here, they will not get off by death. to the preceding action succeeds the natural consequence, worse to the bad, better to the good [Laws 904d].
— The Enneads, III.ii.8 (pp. 80-81)

Accidents and Wrong-doing
But what of chastisements, poverty, illness, falling upon the good outside of all justice? Are they therefore to be charged to past misdoing? No; such misfortunes do not answer to reasons established in the nature of things but were merely accidental sequents. A house falls, and anyone that chances to be underneath is killed, no matter what sort of man he be. The undeserved stroke might be no evil to the sufferer in view of the beneficent interweaving of the All.
    Wrong-doing from man to man is wrong in the doer and he is not to be absolved from responsibility; but as belonging to the established order of the universe is not a wrong even as regards the innocent sufferer; it is a thing that had to be, and if the sufferer is good, the issue is to his gain. For we cannot think that this ordered combination proceeds without God and justice, even though the reasons of things elude us, and to our ignorance the scheme presents matter of censure.
— The Enneads, IV.iii.16 (pp. 124-125)

Problems of the Soul
Anyone that adds his evil to the total of things is known for what he is and, in accordance withhis kind, is pressed down into the evil he has made his own, and upon death goes by the pull of natural forces to the place that fits his quality.
    Thus this universe of ours is a wonder of power and wisdom, everything by a noiseless path coming to pass according to a law which none may elude— which the base man never conceives though it is leading him, all unknowing, to that place in the All whither he must be borne; which the just man knows, and, knowing, sets forth, understanding before he departs where he shall be housed in the end and having good hope that it may be with the Gods [Phaedo 80e].
— The Enneads, IV.iv.45 (p. 139)

The Soul's Descent Into Body
Thus, in sum, the Soul, a divine being and a dweller in the loftier realms, has entered body; it is a god, a later phase of the Divine: but under stress of its tendency to bring order to its next lower, it penetrates to this sphere in a voluntary plunge; if it turns back quickly, all is well; it will have taken no hurt by acquiring the knowledge of evil and coming to understand what sin is, by bringing into play those activities which, potential merely in the unembodied, might as well never have been even there if destined never to come into actuality.
    The nature of the Soul, then, is twofold, being of divine station but skirting the sense-known nature; thus, while it communicates to this realm something of its own store, it absorbs in turn whenever it plunges in an excessive zeal to the very midst of this sphere; though even thus it is always able to recover itself by turning to account the experience of what it has seen and suffered here, learning so the greatness of existence in the Supreme and more clearly discerning the finer things by contrast with their opposites. The experience of evil brings the clearer perception of good.
— The Enneads, IV.viii.5, 7 (pp. 149-150)

Soul's Forgetfulness of the Divine
The evil that has overtaken them has its source in self-will, in the entry into birth, in the desire for self ownership. They conceived a pleasure in this freedom and largely indulged their own motion; thus they were hurried down the wrong path, and drifting further and further, came to lose even the thought of their origin in the Divine. Children wrenched young from home and brought up at a distance will fail in knowledge of their parents and themselves; in the same way the souls no longer discern either the Divinity or their own nature; ignorance of their rank brings self-depreciation; all their awe and admiration is for the alien, and clinging to this they have broken away as far as a soul may; their regard for the mundane and their disregard of themselves bring about their utter ignoring of the Divine.
    Admiring pursuit of the external is a confession of inferiority; and nothing holding itself inferior to things that rise and perish, nothing counting itself less honorable and enduring than all else it admires could ever form any notion of either the nature or the power of God.
— The Enneads, V.i.1 (pp. 154-155)

Omnipresence of Authentic Existent
The soul, sprung from the Divine, lay self-enclosed at peace, true to its own quality; but its neighbor, body, in uproar through weakness, unstable of its own nature and beaten upon from without, of itself and cried out to the compounded being and spread its own disorder to the whole. Thus at an assembly the elders may sit in tranquil meditation, but an unruly populace, crying for food and casting up a host of grievances, will bring the whole gathering into ugly turmoil; when this hold their peace so that a word from a man of sense may reach them, some passable order is restored and the baser faction ceases to prevail; otherwise the silence of the better allows the rabble to rule, the distracted assembly unable to take the word from above.
    This is the evil of man; man includes an inner rabble— pleasures, desires, fears— and these become masters when he gives them play. But one that has reduced his rabble and become again the Man he was, lives to that, so that what he allows to the body is granted as to something separate.
— The Enneads, VI.iv.15 (pp. 186-187)