What does the word "letter" mean?

The ethical category of confucianism. Honesty, that is, honesty, trustworthiness and non-hypocrisy, is one of the important conditions for Confucianism to realize the moral principle of benevolence and one of the contents of Confucian moral cultivation. Confucius and his disciples put forward the belief that people should keep their promises to each other according to the rules of etiquette in order to adjust the contradiction between the ruling class and the opposing class. Confucianism regards "faith" as the foundation of building and governing the country. Han Confucianism listed the "faith" in the Analects of Confucius among the "five permanent members": "I save three times a day, how can I be disloyal to others?" Don't believe in making friends? Can you pass it on? .. the letter is close to the righteousness, and the words can be answered. "Zuo zhuan. "Two Years of Gong Xuan": "Meng Ke retired and sighed:' Don't forget the venerable, the Lord of the people. Thieves and owners of people. Infidelity; Give up your life. If you don't believe this, you might as well die. "