Chapter 5, Part 2B - Lieh Tzu

'Heaven and earth, then, are themselves only material objects, and therefore imperfect. Hence it is that Kua of old fashioned many-colored blocks of stone to repair the defective parts.

'He cut off the legs of the Ao and used them to support the four corners of the heavens.

'Later on, Kung Kung fought with Chuan Hsü for the throne, and, blundering in his rage against Mount Pu-chou, he snapped the pillar which connects Heaven and earth.

'That is why Heaven dips downwards to the north-west, so that sun, moon and stars travel towards that quarter. The earth, on the other hand, is now not large enough to fill up the south-east, so that all rivers and streams roll in that direction.'
~ Lionel Giles translation via Terebess Asia Online ~

Go here to read the introductory post to the chapters of the Book of Lieh Tzu.