The sublime attitudes, are attitudes of goodwill, compassion, empathetic joy, and equanimity that you spread to all beings, without limit. Each of these attitudes is an antidote for mental states that can get in the way of training the mind. For this reason, they play an important role in fostering the path to the end of suffering.
• Goodwill, mettā, a wish that beings will be happy, is an antidote for ill will, the desire to see beings suffer. Notice that we don’t translate mettā as love or loving-kindness, because, as the Buddha pointed out, love is partial, and can easily turn into hatred. When you’re advised to develop universal mettā, you’re not being asked to love everyone, or even to like everyone. Instead, you’re simply asked not to want to see anyone suffer, regardless of whether you like that person or not.
• Compassion, karuṇā, a wish that those who are suffering will be freed from their suffering, is an antidote to cruelty, the desire to actually harm others when they’re down.
• Empathetic joy, muditā, a wish that those who are already happy will continue to be happy, is an antidote to resentment and envy.
• Equanimity, upekkhā, the ability to maintain the mind on an even keel when events don’t fall in line with your goodwill, is an antidote to irritation.
Notice that you practice developing these attitudes toward all beings—including yourself. To do this, you have to develop them consciously, because in the normal human heart these attitudes tend to be partial. It’s easy to feel goodwill, for example, for those you like, or equanimity toward those who have no connection to you. But it requires a conscious effort to be able to maintain these attitudes toward anyone and everyone. It’s not the case that the brahmavihāras are the heart’s innate nature. After all, their opposites can come just as naturally to the heart. It’s just as natural to feel ill will for those who have betrayed you or people you love as it is natural to feel goodwill for those who behave in ways you like. It’s just as natural to get irritated when things don’t go your way as it is to be equanimous when nothing disturbs you.
So in making your goodwill and equanimity limitless, you’re learning to take these human attitudes that tend to be partial and to intentionally erase any trace of partiality in how you apply them. In doing so, you lift your human mind to the level of the Brahmās, the highest level of heavenly beings, who have developed the sublime attitudes to the point where they can extend them to everyone, no matter who, no matter where.
https://www.dhammatalks.org/books/SublimeDeterminations/Section0004.html