[lè bù kě jí]   

乐    不    可    极    享乐不可过分。

享乐不可过分,否则乐极生悲。也比喻做事要有限度

One should not pursue pleasure to its extreme

乐往哀来    乐极生悲    乐道好古    乐以忘忧    乐成人美