Enneads III.6: Of the Impassibility of Incorporeal Entities (Soul and and Matter)
Psychological Explanation of Anger-part's Courage or Cowardliness
But how can the soul's irascible-part[36] be at one time courageous, and at the other cowardly? When it is cowardly, it does not consider reason, or considers reason as having already become evil; or because the deficiency of its instruments, that is, the lack or weakness of its organs, hinders it from acting, or feeling emotion, or being irritated. In the contrary condition it is courageous. In either case, the soul undergoes no alteration, nor is affected.