In chapter 9 Matt deals with Paul's statement, "Rejoice in the Lord always, again I say rejoice." That can be a lofty goal, but how does it work itself out in reality. Matt shares a time in his own life when something tragic is happening. When your son is in an ambulance, your wife is with him, and you are following in your car, but you don't have lights and a siren. And when you lose them, you realize you don't even know which hospital they are taking him to. How do you rejoice in that moment?
You rejoice because your joy is not based on your circumstances, but it is based on your belief that God is in control, that He sees everything, and that He is in charge. Not a sparrow falls to the ground and he is not aware.
This is not a sappy, I will be happy no matter what. That does not glorify God. It is the fact that we can have assurance even in the midst of tragedy. That even though things don't go the way we desire, we still trust in God. Completely. Rejoice.