人心无底洞填不满也掏不空
[rén xīn wú dĭ dòng tián bù măn yĕ tāo bù kōng]
'人心无底洞填不满也掏不空' translates to 'A human heart is like a bottomless pit—never filled and never empty'. It represents an understanding of complex human emotions, suggesting that human desires and feelings are inexhaustible.