空穴來風未必無因 [ㄎㄨㄥˋ ㄒㄩㄝˊ ㄌㄞˊ ㄈㄥ ㄨㄟˋ ㄅㄧˋ ㄨˊ ㄧㄣ; kong4 xue2 lai2 feng1 wei4 bi4 wu2 yin1] wind does not come from an empty cave without reason there's no smoke without fire (idiom) ◄ ►