‘青出于蓝’ is a classical Chinese idiom literally meaning ‘indigo blue emerges from the indigo plant.’ In ancient China, indigo dye was extracted from the leaves of the woad plant (a type of flowering plant in the Brassicaceae family), yet the resulting dye was deeper and bluer than the original plant — hence the phrase symbolizes that a student or disciple surpasses their teacher in skill, knowledge, or achievement. Though it contains the character 青 (qīng), which can mean ‘blue’ or ‘green,’ here it specifically refers to the processed indigo pigment.

The idiom originates from the Confucian text Xunzi and is widely used in educational, artistic, and professional contexts to praise exceptional growth or mastery beyond one’s mentor. It carries a positive, respectful connotation — not implying rivalry, but rather honoring the teacher while acknowledging the student’s outstanding progress. It’s often paired with the full phrase ‘青出于蓝而胜于蓝’ (qīng chū yú lán ér shèng yú lán), emphasizing the ‘surpassing’ aspect.