10 ideas
A single moment of anger toward a bodhisattva destroys the good deeds, generosity, and worship built up over a thousand aeons. No evil equals hatred and no austerity equals patience. Anger is therefore the most costly mental event, because it wipes out prior progress as well as causing present harm.
Someone who harms you creates the conditions for practicing patience, which cannot be practiced without an antagonist. You should welcome the enemy like a treasure that appears in your house without effort. The insulter becomes a necessary teacher, and you owe them gratitude.
If a situation can be remedied, there is no reason for dejection; act on it. If it cannot be remedied, dejection is useless. In both cases distress adds nothing, so the energy belongs in action or acceptance.
People who harm us do not choose freely to become angry. Their anger arises from causes and conditions, the way bile causes illness without intending to. Blaming them is as incoherent as raging at a disease.
Shantideva notes that we skip the stick and get angry at the person wielding it, though that person is in turn driven by hatred, so if anger must land anywhere it should be on the hatred. He then points to your own share in the harm: you once caused similar suffering to others, and while the harmer supplied the weapon, you supplied the body that can be hurt. Seeing yourself as a co-cause undercuts the grounds for anger at the other person.
You cannot find enough leather to cover the whole earth, but leather on the soles of your feet has the same effect. Likewise you cannot subdue every hostile person, but subduing your own mind subdues them all. Control shifts from the external world, which cannot be managed, to inner response, which can.
Anger feeds on mental discomfort that arises when unwanted things happen or wanted things are blocked. If you remove that fuel early by refusing to let the mind become disturbed, anger has nothing to grow from. Keeping a cheerful mind is therefore the practical first line of defense against hatred.
Nothing is difficult once you are accustomed to it, so endurance of small discomforts trains endurance of greater ones. Start with minor irritations like insect bites, heat, cold, and hunger, and build tolerance progressively. Patience grows as a trained habit, not as a sudden virtue.
Praise and fame bring no merit, long life, strength, or health, and they only feed distraction and pride. Getting angry when others obstruct your reputation is like children crying when their sandcastles are knocked down. Those who block your honor actually free you from a trap.
Since everyone equally wants happiness and avoids suffering, there is no principled reason to prioritize your own pain over another's. Deliberately place yourself in the other's position and treat their suffering as yours. Self-cherishing is identified as the root of all misery, and cherishing others as the root of all happiness.