Virtue comes from Yi Zhuan, which means that people should have noble moral character as profound as the earth.

Erudition comes from The Book of Rites. The golden mean is to be knowledgeable and ask if you don't understand.

The unity of knowing and doing is a theory put forward by Wang Yangming, a famous thinker in the Ming Dynasty, which advocates that knowing and doing are indistinguishable from doing.

Together, it refers to an educational concept. Educators should have profound and noble character, profound knowledge, the spirit of asking if they don't understand, apply what they have learned, and knowledge can't be divorced from action.