The book builds its case on a simple observation: a person who feels safe acts on a longer horizon, and a person who is afraid acts on a short one.
A chapter is given to what the author calls “decisions of fear” — the ones that look reasonable at the moment they are made and are hard to explain a week later.
What matters most in the book is that it does not treat tranquillity as a feeling to be waited for, but as a state built by means, some devotional and some purely practical.