All these constructions and the laws connecting them can be arrived at by the principle of looking for the mathematically simplest concepts and the link between them.
The most important human endeavor is the striving for morality in our actions. Our inner balance and even our very existence depend on it. Only morality in our actions can give beauty and dignity to life.
It's not that life has been easy, perfect or exactly as expected. I just choose to be happy and grateful no matter how it all turns out. If people are good only because they fear punishment, and hope for reward, then we are a sorry lot indeed.