子非鱼安知鱼未忆子非我怎知我情深
[zi fēi yú ān zhī yú wèi yì zi fēi wŏ zĕn zhī wŏ qíng shēn]
Translates loosely to 'You're not a fish so how would you know if the fish is remembering? You're not me, so how do you understand my profound feeling'. This indicates the idea that no one else can fully comprehend another’s memories or emotions.