In terms of social practical value, what is useful for social practice and social life application is called "useful"; On the contrary, it is "useless". In a broad sense, those with social or application value are called "useful" and vice versa.

Famous sayings

1. Everyone knows what is useful, but he doesn't know what is useless. What is useless is for great use. -Zhuangzi

2. No matter what kind of knowledge you master, it is useful for intelligence. It will throw away useless things and keep good things. -up to? Finch

3. Being useful means slavery. Useless means that you only exist for yourself, and uselessness is the real freedom. Because it is useless, it can be used for personal use. -Zhang Fangyu

4. Things that taste good in the world, including poetry, wine, philosophy and love, are often useless. Singing useless poems, drinking useless wine, reading useless books, and sounding useless, I finally became a useless person, but I lived a delicious life. -Zhou Guoping's Leisure

5. Reading some useless books, doing some useless things and spending some useless time are all in order to keep an opportunity to surpass yourself in addition to all the known. Some great changes in life come from this moment. -Liang Wendao's "Yue Ji"