From Courage Under Fire:
"On September 9, 1965, I flew at 500 knots right into a flak trap, at tree-top level, in a little A-4 airplane--the cockpit walls not even three feet apart--which I couldn't steer after it was on fire, its control system shot out. After ejection I had about thirty seconds to make my last statement in freedom before I landed in the main street of a little village right ahead. And so help me, I whispered to myself: 'Five years down there, at least. I'm leaving the world of technology and entering the world of Epictetus.'
'Ready at hand' from The Enchiridion as I ejected from that airplane was the understanding that a Stoic always kept separate files in his mind for (A) those things that are 'up to him' and (B) those things that are 'not up to him.' Another way of saying it is (A) those things that are 'within his power' and (B) those things that are 'beyond his power.' Still another way of saying it is (A) those things that are within the grasp of 'his Will, his Free Will' and (B) those things that are beyond it. All in category B are 'external,' beyond my control, ultimately dooming me to fear and anxiety if I covet them. All in category A are up to me, within my power, within my will, and properly subjects for my total concern and involvement. They include my opinions, my aims, my aversions, my own grief, my own joy, my judgments, my attitude about what is going on, my own good, and my own evil."
James B. Stockdale. Courage Under Fire: Testing Epictetus's Doctrines in a Laboratory of Human Behavior (Hoover Essays) (Kindle Locations 108-116). Kindle Edition.