It means: three people go together, and there must be my teacher among them. I choose his good aspects to learn from him, and when I see his bad aspects, I correct my shortcomings for myself.
This sentence shows the spirit of Confucius' self-cultivation and humility. It includes two aspects: on the one hand, it is the spirit of being open-minded and eager to learn; On the other hand, people who have not changed well should take warning from their shortcomings and reflect on themselves. This is the spirit of self-cultivation. In this way, no matter how good or bad people get along, they can be teachers. It is recorded in The Analects that Gong Sunchao once asked Zi Gong about defending the country. Where did Confucius learn his knowledge? Zi Gong replied that the ancient sage's preaching remained among the people, and the sage knew the bigger point, while the wicked knew the smaller point. There are ancient saints. "Why didn't the master stop learning and often invited teachers?" (The Analects of Confucius, Zhang Zi) He learns from everyone anytime and anywhere. Anyone can be his teacher, so there is no fixed teacher. There are many records in The Analects of Confucius, such as Confucius entering the ancestral temple and "asking everything" (The Analects of Eight Shu); Zaiyu slept during the day, and Confucius said, "I started with others, I listened to what I said and believed what I did;" Today, I am also a person, listening to his words and observing his actions. Giving and changing are. " (The Analects of Confucius, Gongye Chang) Zi Gong told Confucius that Zi Gong could only "smell one and know two", but Yan Hui could "smell one and know ten". Confucius said, "The Buddha is as good as it is. "I'm just like you." (The Analects of Confucius Gongye Chang) embodies this spirit. This spirit and attitude is worth learning.