《淮南子·道应训》
像我向南游过的无边无际的空旷之地，在北方休息在寂静幽暗的地方，向西跑遍幽深边远的地方，往东一直来到日出之处。这些地域是下无地而上无天，听不到任何声音，看不清任何物件。
若我南游乎冈之野，北息乎沉墨之乡，西穷窅冥之党，东开鸿濛之光，此其下无地而上无天，听焉无闻，视焉无眴，此其外，犹有汰沃之汜。
Like the boundless empty place I swam to the south, resting in the quiet and dark place in the north, running around the deep and remote place to the west, and going all the way to the sunrise in the east. These areas have no land below and no sky above, and I can't hear any sound or see any objects.