再美的回忆也只是过去再美的记忆也只是曾经
[zài mĕi de huí yì yĕ zhĭ shì guò qù zài mĕi de jì yì yĕ zhĭ shì céng jīng]
Signifies that despite how beautiful memories can be, they remain as only past events. It conveys nostalgia and the understanding that memories can never relive their original beauty once time passes.