朝气蓬勃

Origin and story

This expression combines the fresh energy of morning with vigorous flourishing. The Ministry of Education dictionary defines it as lively, spirited vitality but supplies no ancient event or named inventor. A well-documented twentieth-century use occurs in Mao Zedong's address to Chinese students in Moscow, where young people are compared with the morning sun.

That speech is an attestation, not sufficient evidence that it created the phrase. In ordinary use, the expression praises the energy and hopeful activity of a person or group; it need not imply that everyone described is literally young.