The easiest way to distinguish between our emotions is to examine their motivation (mental attitude and objective) and their results. If an emotion strengthens our inner peace and seeks the good of others, it is positive, or constructive; if it shatters our serenity, deeply disturbs our mind and is intended to harm others, it is negative, or afflictive. As for the outcome, the only criterion is the good or the suffering that we create by our acts, words and thoughts, for ourselves as well as for others.
That is what differentiates, for instance, ‟holy anger” — indignation before injustice — from rage born of the desire to hurt someone. The former has freed people from slavery and domination and moves us to march in the streets to change the world; it seeks to end the injustice as soon as possible or to make someone aware of the error of his ways. The second generates nothing but sorrow.
As the Tibetan poet Shabkar said: ‟One with compassion is kind even when angry; one without compassion will kill even as he smiles.”