A gentleman has three precepts: when he is young, his blood gas is uncertain, so quit it; It is also strong and bloody, and it is fighting; Even when you are old, your blood is failing, so you should quit. ? It means that when you are young, your blood gas is immature and you abstain from color; In the prime of life, the blood is strong, so don't be competitive; When you are old, your blood is weak, so you should abstain from greed.