Via Daily Dharma / Necessary Anger

Anger toward social injustice will remain until the goal is achieved. It has to remain.

Of course. That anger is directed toward the social injustice itself, along with the struggle to correct it, so the anger should be maintained until the goal is achieved. It is necessary in order to stop social injustice and wrong destructive actions.

—His Holiness the Dalai Lama, "The (Justifiably) Angry Marxist"