Inter-relation between the four brahmaviharas? I read once, online, someone (perhaps in the Tibetan tradition if that matters) saying that the four brahmaviharas are inter-related -- in particular, that too much of one is counteracted by a bit of another.

For example:


Feeling too sorry for someone (too much compassion/karuna) is counteracted by a bit of mudita (remembering the ways in which that person is virtuous or fortunate)
Similarly, too much of each of the other three is counter-balanced by a bit of each of the others


I was reminded of it by this answer ("in good there is seed of bad").

I don't remember the explanation I read, though, and I wasn't able to find the reference again.

Is that anything you've heard before? If you know the explanation but don't know a reference for it, that's OK too (I'd be happy to read just your explanation of it even without a reference).
Uppekkha is what is used to straighten Karuna. Not Muditha. Compassion can easily turn into sadness. When that happens you view the situation in terms of Karma and Vipaka: “All beings are the owners of their karma; their happiness and unhappiness depends upon their actions, not on my wishes for them.”

Metta(kindness) can turn into lust when practiced towards attractive women. Then you can use a mental technique like thinking of them as mothers, sisters, daughters or you can meditate on the repulsiveness of the body.