往事深去少年蓝
[wăng shì shēn qù shăo nián lán]
The phrase '往事' (wangshi) refers to past memories or nostalgia. The word '少年' (shao nian) stands for youth or teenagers, while '蓝' (lan) symbolizes melancholy. Overall, it implies a feeling that youthful innocence is long gone.