Seneca's central point in On Anger

 Seneca's central point in On Anger is that anger and silence are not the only two options. He thinks they are both failures of reason. Anger is a brief madness in which you let the other person's behavior decide your state of mind. Silence, if it comes from swallowing something you are still seething about, is just anger hiding. What he recommends instead is calm firmness: you say what needs saying, set the limit that needs setting, and correct what needs correcting, but you do it as a decision rather than a reaction. He borrows a line he attributes to Plato, that a wise person punishes not because someone has done wrong but so that it will not happen again. Correction is aimed at the future, while anger is aimed at the past and wants payback. He also argues against the view that anger gives you useful energy. A good advocate, general, or parent can be forceful without it, and anger makes you worse at the thing you are trying to accomplish because it clouds judgment and gives the other person power over you.

His practical tools mostly work by preventing anger before it starts. The first is to expect people to be foolish, careless, ungrateful, and self-interested, since that is the normal human condition, and you will be much harder to surprise or offend. He asks you to remember that you too are a source of irritation to others, and to give people the leniency you would want for yourself. He also advises not investigating every slight or rumor: much of what angers us is half-heard, misread, or never meant for us, and giving people the benefit of the doubt keeps your mind quieter. Then there is delay, which he calls the greatest remedy for anger. If you feel it rising, lower your voice, slow your pace, and let a day pass before you answer. By then, the matter often looks smaller, or at least you can speak about it in a measured way. He also recommends an evening review of your day, asking what you handled badly and what you would do differently, with the aim of improving rather than punishing yourself.

As for succeeding with people, Seneca is a pragmatist about company. In his letters and in On Tranquility of Mind he advises being slow to choose friends and then trusting the ones you choose completely, avoiding the hot-tempered and the chronically resentful because their moods are contagious, and not scattering yourself across too many entanglements. Success in his sense is less about winning arguments and more about keeping your composure and reputation for steadiness, so that people come to see you as someone whose word is measured and whose reactions are not triggered by provocation. He also says speech should be plain and honest, like a good conversation, without display or point-scoring. So when something needs to be said, say it directly and at the right moment, in a tone you would still be comfortable with a day later. If you cannot do that yet, wait, because a short delay is wiser than either an outburst or a resentful silence.