Bié bēigōngshéyǐng le, nà zhǐshì fēng chuī de shēngyīn.
Stop imagining things — that is just the sound of the wind.
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From 应劭《风俗通义》(Han dynasty): a man saw what he thought was a snake in his wine cup and fell ill with fear. It turned out to be the reflection of a bow hanging on the wall. Once he realized the truth, he recovered.