Can't judge a book by its cover
不能僅憑外表判斷人或事物，強調內在價值與表面不符。
提醒勿以貌取人或輕視外表普通的事物。
英文釋義
Cannot judge something primarily on appearance.
例句
He looks scruffy, but you can't judge a book by its cover; he's a genius.
典故來源
源自19世紀美國出版業，提醒讀者勿以裝幀判斷內容，后泛化。