We can figure out if anger is natural by looking at human nature itself. What could be gentler than a person in their right mind? But what could be crueler than anger? What creature cares more about others than humans do? But what turns more savage against them than anger does? We are born to help each other. Anger exists to destroy each other. We naturally love community. Anger loves isolation. We want to do good. Anger wants to do harm. We help even strangers. Anger attacks even our closest friends.
Whether it be according to nature will become evident if we consider man's nature, than which what is more gentle while it is in its proper condition? Yet what is more cruel than anger? What is more affectionate to others than man? Yet what is more savage against them than anger? Mankind is born for mutual assistance, anger for mutual ruin: the former loves society, the latter estrangement. The one loves to do good, the other to do harm; the one to help even strangers, the other to attack even its dearest friends.