Failure doesn't teach you anything, the reflection afterward does
The lesson is never inside the failure itself. It is inside the quiet you find three weeks later, or three months later, when the sting has dropped enough for you to look straight at what happened. Chanakya wrote in the Arthashastra that a man who cannot examine his own defeat is already preparing for the next one. He was describing a structural problem: the mind under pressure is a bad analyst. It is too busy managing shame, or anger, or the performance of moving on.
