見るに堪えない vs 感謝に堪えない — same に堪えない, opposite emotional direction?

Question

I've seen に堪えない used for something so bad it's unbearable to watch (見るに堪えない光景), and also for gratitude so overwhelming it can't be contained (感謝の念に堪えない). Are these really the same grammar point, or did two different meanings just converge on the same surface form?

Accepted Answer

同一個文型，但確實分成兩種用法：接在「見る、聞く、読む」這類感官動詞後面＝「不忍…、不堪…」（太糟糕以致於無法承受）；接在感情名詞（感謝、感激、遺憾）後面＝「不勝…」（強烈到無法壓抑）。兩者共通點是「程度強到超出承受範圍」，只是一個是負面痛苦、一個是正面激動，方向剛好相反但底層邏輯一致。