安如少年秋如梦旧时凉梦已成空
[ān rú shăo nián qiū rú mèng jiù shí liáng mèng yĭ chéng kōng]
Expressed as 'As peace as the young man, as fall is like a dream, cool recollections have turned to naught', indicating the tranquil state akin youth and viewing past events in a reminiscent way, now those memories vanished without trace just leaving nostalgia left over.