I like the quote as well. Anger is a necessary emotion like all the others. However do we let it out or keep it in? I will not answer the question as it depends on the situation. It is all about how to control the situation as keeping it in is not healthy. It become problematic when one is consumed by it and then it is not an incidental state but a permanent state. Too much energy is expended when angry - solutions are not attained when in this state. It is also damaging to the angry person over time. Also it does not appease the situation if one is angry with someone else. Controlling anger is the key.