On Anger, Book I, IX

In the next place, anger has nothing useful in itself, and does not rouse up the mind to warlike deeds: for a virtue, being self-sufficient, never needs the assistance of a vice: whenever it needs an impetuous effort, it does not become angry, but rises to the occasion, and excites or soothes itself as far as it deems requisite, just as the machines which hurl darts may be twisted to a greater or lesser degree of tension at the manager’s pleasure.

“Anger,” says Aristotle, “is necessary, nor can any fight be won without it, unless it fills the mind, and kindles up the spirit.

It must, however, be made use of, not as a general, but as a soldier.”

Now this is untrue; for if it listens to reason and follows whither reason leads, it is no longer anger, whose characteristic is obstinacy: if, again, it is disobedient and will not be quiet when ordered, but is carried away by its own willful and headstrong spirit, it is then as useless an aid to the mind as a soldier who disregards the sounding of the retreat would be to a general.

If, therefore, anger allows limits to be imposed upon it, it must be called by some other name, and ceases to be anger, which I understand to be unbridled and unmanageable: and if it does not allow limits to be imposed upon it, it is harmful and not to be counted among aids: wherefore either anger is not anger, or it is useless: for if any man demands the infliction of punishment, not because he is eager for the punishment itself, but because it is right to inflict it, he ought not to be counted as an angry man: that will be the useful soldier, who knows how to obey orders: the passions cannot obey any more than they can command.