若颜回不去的曾经夕颜想不起的回忆
[ruò yán huí bù qù de céng jīng xī yán xiăng bù qĭ de huí yì]
It's somewhat poetic, implying fleeting beauty and memory ('Ruo Yan' and 'Xi Yan' are not names but refer more likely to blooming times of flowers), which evokes nostalgia about things or persons passed, suggesting they can never return back like those faded past and unrecalling memories.