花有从开日人无再少年
[huā yŏu cóng kāi rì rén wú zài shăo nián]
'Flowers Have Blooming Days but Man Never Returns to Youth' compares the natural cycle of blooming flowers with human aging. This idiom means things can return to a former flourishing state but youth, once passed, can never be relived, symbolizing irreversible changes in time.