What is the rarest: bravery in battle, great intelligence, or moral courage?
This is not a trick question yet answering it or living it is.
Hemingway wrote in A Farewell to Arms in 1929 “Few men are willing to brave the disapproval of their fellows, the censure of their colleagues, the wrath of their society. Moral courage is a rarer commodity than bravery in battle or great intelligence. Yet it is the one essential, vital quality of those who seek to change a world which yields most painfully to change.”
Serenity supports a life of moral courage so that the choices which truly benefit others supports the honest person which Diogenes.