A circle of emotions

Emotion behavior has some rules.
Emotions are one type of function to keep one's mind healthy, and so there is some curtain rules in their behavior, just like an ball.

One fundamental rule is this, "One always choose to be in a pleasant state."
The original feeling of humans is pleasant. So, when it disturbed by something (doesn't matter whether by humans or not), one try to come back to the pleasant state by going through four main emotions. The emotions are "anger," "sorrow," "reflection," "forgiveness." The circle starts with either anger or sorrow. You may first get angry then feel sad, or vice versa, but the later two come in order.
For example, if I get a bad mark on a test, at first I'll think "Why the teacher gave so difficult questions?" or "Why I missed that easy one?" then, "... but, may be I should've studied more..." Then finish with, "Oh, well. I'll do better in the next time." The first two phrases can be both anger or sadness, but anyway, I'll feel both of them one by one. After felt both anger and sad comes the third phrase which is a reflection, and come back to the original state with the forth phrase which is a forgiveness to myself.

Whenever there is a disturbance, one follows this circle, but the size of the circle depends on the magnitude of the disturbance. So when there is a painful event, like loved ones death, it often takes a long time to finish the circle.