《淮南子·说林训》
太阳从旸谷升起，到虞渊落下，没人知道它是怎么运行的，片刻间就偏西了，人只须反转头颈就能看到。
日出旸谷，入于虞渊，莫知其动，须臾之间，俛人之颈。
The sun rises from Yanggu and sets in Yu淵, no one knows how it operates, and in a moment it will be in the west, and people can see it by just turning their heads.