(one's) better nature
The best aspects of one's character, especially one's generosity, magnanimity, mercy, or empathy. I wouldn't bother trying to appeal to his better nature—the boss doesn't look on requests for charity lightly. With this fundraiser, we're hoping people's better nature shines through to help the millions in need following the natural disaster. Mr. Stewart may yell a lot, but I've seen his better nature come through—he's actually helped me carry my groceries many times.
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