(Armstrong Selection and Translation from the Enneads AP)
A comment on some Platonic texts from the Theaetetus and Timaeus : evil must necessarily exist (i) because matter is necessary to the existence of the visible universe; (ii) because the process of outgoing or down-going from the Good must have a limit, and this limit is Matter, which has no good in it at all. (Ennead I. 8.7)
Matter is absolutely evil because it is an absolute deficiency of good. (II. 4. 16 (end))
Matter, Plotinus has just said, is not body or soul or mind or life or form or limit or potency. He proceeds to describe its essential falseness and unreality, its phantasmal character, and that of the material things which are formed in it. (III. 6. 7)
The principle of evil is absolute formlessness as opposed to form, non-being as opposed to being, i.e. Matter. (I. 8. 3)
The difference between matter in the Intelligible World (the unformed living potency of Soul or Noûs, turning in a timeless process to that which is above it to receive form) and the dead matter of the world of the senses. (II. 4. 5)