曾我心欢喜曾我空欢喜
[céng wŏ xīn huān xĭ céng wŏ kōng huān xĭ]
It reflects on past happiness and subsequent disillusionment – there was once joy when hope was fulfilled ('曾我心欢喜'), but it turns out all in vain or leading to disappointment ('曾我空欢喜'). This expresses regret for lost illusions.