《史记·十二本纪·高祖本纪》
高祖感到奇怪，就问吕后，吕后说： 你所处的地方上面常有云气，向着有云气的地方去找，常常可以找到你。 
高祖怪问之。吕后曰： 季所居上常有云气，故从往常得季。 
The High Ancestor was surprised, and so he asked Lü Hou how she had done it. She replied: "There is often a cloud of mist above you. I searched in the direction of the mist and often managed to find you."