青出于蓝而胜于蓝 means that indigo blue is obtained from the indigo plant, but such color is bluer than the plant itself. It is used as an analogy to describe students surpassing their teachers. Below is a story about the origin of this proverb:

荀子,本名叫荀况,国时期赵国人,是一位著名的唯物主义思想家,是春秋战国时期思想界的杰出代表。他把一生研究的成果,都保留在他的著作《荀子》这本书里,系统地反映了他的哲学、教育和政治思想。

"劝学"是《荀子》三十二篇中的第一篇。作者在这篇文章中,比较全面地论述了学习目的、意义、态度和方法,对人们具有深刻的启迪作用。文章中有这样一段话: "学不可以己。青,取之于蓝,而青于蓝;冰,水为之,而寒于水。"意思是:学习是不应当停止和废弃的。青色是从蓝色的染料里提取出来的,可是它比蓝色还要青;冰是水结成的,可是它比水还要凉。

在这里,荀子以青与蓝,冰与水的关系作比喻,说明学生只要通过坚持不懈地刻苦学习,就能够有所提高,学生一定要有志气超过自己的老师,一代要比一代强。

"青出于蓝而青于蓝"这句名言,最早就是荀子说的。 后来,这几句话演变为"青出于蓝而胜于蓝"这句谚语,用以比喻学生胜过先生,后人胜过前人。

Chinese philosopher Xunzi, who was also known as Xun Kuang, was a well-known thinker of materialism during the the Warring States period. He was an outstanding representative of the intellectual world of the Spring and Autumn period. He preserved the results of his life in his book, Xunzi, which systematically reflected his philosophy, education and political thinking.

"Encouraging Learning" is the first of 32 chapters in Xunzi. In this article, the author discusses the purpose, meaning, attitude and method of learning comprehensively. It has profound enlightening effect on people. The article has such a passage: "Learning never ends. Green comes from the blue, and green is bluer than blue; ice comes from water and is colder than water." It means: learning should not be stopped and abandoned. Green is extracted from the blue dye, but it is even bluer than blue; ice is formed of water, but it is cooler than water.

Xunzi used green and blue, ice and water as a metaphor, stating that as long as the students has the perseverance to study hard, they can improve, and students must have more ambition than their teachers, so the next generation is stronger than the previous generation.

"Green comes from blue and is bluer than blue" is one of the earliest Xunzi saying. Later, these words evolved into "Green come from blue and is better than blue." This proverb is used to describe the students that are better than their predecessors.