百胜难虑敌，三折乃良医
bǎi​shèng​nán​lǜ​dí​sān​zhé​nǎi​liáng​yī

failure is the mother of success

百胜难虑敌，三折乃良医 百勝難慮敵，三折乃良醫 bǎi​shèng​nán​lǜ​dí​sān​zhé​nǎi​liáng​yī
failure is the mother of success
One learns more from one's failures than from one's successes; literary expression by 刘禹锡 liú​yǔ​xī literally meaning that a hundred victories make it hard to evaluate an enemy, while breaking one's arm three times makes one a good doctor