To possess great talent or virtue despite a humble or plain appearance; to be a person of real worth hidden by a modest exterior.
他虽然平时不爱炫耀，总是穿着朴素，但每次解决问题都能展现出非凡的智慧，真是被褐怀玉。
Although he usually doesn't show off and always dresses plainly, every time he solves a problem, he displays extraordinary wisdom; he truly embodies the spirit of "wearing coarse clothes and carrying jade."
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