All things that happen, have happened, and will happen -- they all are natural. There's no need to fear, to wonder, or to be surprised by them. We are here to help one another. To be of use to others is natural. Death is also natural. Mind is who we are. We should free our mind from all immoderations, feelings, our own misperceptions, and other contaminations. The present is all we have to live in, or to lose.
That book actually contains much more than what I could sum up. I will have to say that Marcus Aurelius was so stoic.