Be calm in arguing: for fierceness makes
Error a fault, and truth discourtesy.
Why should I feel another man's mistakes
More, than his sickness or poverty?
In love I should: but anger is not love,
Nor wisdom neither: therefore gently move.

We must calm the mind of the common man, and tell him to abstain from the words and even the passions which lead to insurrection.

Be humble and avoid vengefulness, he advised. “Being a king means not to be wealthy. It means not bullying others.

The calm man, having learned how to govern himself, knows how to adapt himself to others; and they, in turn, reverence his spiritual strength, and feel that they can learn of him and rely upon him. The more tranquil a man becomes, the greater is his success, his influence, his power for good.

Keep this thought handy when you feel a fit of rage coming on — it isn’t manly to be enraged. Rather, gentleness and civility are more human, and therefore manlier. A real man doesn’t give way to anger and discontent, and such a person has strength, courage, and endurance — unlike the angry and complaining. The nearer a man comes to a calm mind, the closer he is to strength.” — MARCUS AURELIUS, MEDITATIONS, 11.18.5b

I say that every prince ought to desire to be considered clement and not cruel. Nevertheless he ought to take care not to misuse this clemency.

It is easy to be calm when there is nothing to worry about, Eragon. The true test of your self-control, however, is whether you can remain calm in a trying situation. You cannot allow anger or frustration to cloud your thoughts, not at the moment. Right now, you need your mind to be clear.
Have you always been able to remain calm at times like this?
The old dragon seemed to chuckle. No. I used to growl and bite and knock down trees and tear up the ground. Once, I broke the top off of a mountain in the Spine; the other dragons were rather upset with me for that. But I have had many years to learn that losing my temper rarely helps. You have not, I know, but allow my experience to guide you in this. Let go of your worries and focus on the task at hand. The future will be what is will, and fretting about it will only make your fears more likely to come true.
I know, Eragon sighed, but it's not easy.
Of course not. Few things of worth are. Then Glaedr withdrew and left him to the silence of his own mind.

Just Discourse: Do not bandy words with your father, nor treat him as a dotard, nor reproach the old man, who has cherished you, with his age. (tr. Athen. 1912, vol. 1, p. 359)

Lo, what said King Solomon, who can teach us so well? ‘Do not befriend an angry man, and walk not along the way with a madman, lest you repent.’ I will no further say.

To these young men especially, and to all young men I say (as the poet Chapman said to the young Elizabethan): “Be free, all worthy spirits, and stretch yourselves!” Bring all your knowledge of life to bear on everything that you write. Never let yourself bog down in pedantry and detail. Bring history, the most humane and noble form of letters, back to the proud position she once held; knowing that your words, if they are read and remembered, will enter into the stream of life, and perhaps move men to thought and action centuries hence, as do those of Thucydides after more than two thousand years.

Be calm. A man can do but little. Enough if that little be right.

The footman burst in, announcing, 'Monsieur le Duc de — -.'
'Hold your tongue, you fool,' said the Duke as he entered the room. He said this so well, and with such majesty than Julien could not help thinking that knowing how to lose his temper with a footman was the whole extent of this great personage's knowledge.

Be calm in arguing: for fierceness makes
Error a fault, and truth discourtesy.

Keep cool; anger is not an argument.