When there is a certain expectation of a known thing, it often produces a sad feeling, because there is an expectation, the answer and the expected difference will be too great to cause sadness. If the question is unknown, the feeling of sadness will not be present. It seems that sadness is a kind of heartfelt feeling caused by the misjudgment of known things. Looking back at the answer, since sadness is determined to be a kind of misunderstanding caused by the wrong judgment of known things, then the wrong judgment is us. Is it the one who gives us the sadness that caused the sadness? Because I care, I'll be sad. If you care about a person, then your expression will make us sad, if you care about one of your own disabilities, you will not be informed about that disability, and you will feel sensitive when you feel it.