Chapter 13

Index
Look at it, it cannot be seen - it is called the invisible. Listen to it, it cannot be heard - it is called the inaudible. Grasp it, it cannot be held - it is called the intangible.
These three cannot be further inquired into, so they are merged and become one.
Its upper part is not bright, its lower part is not dark.
Continuous and unnameable, it returns to nothingness.
This is called the form of the formless, the image of nothingness; this is called the elusive and indistinct.
Approach it and you cannot see its beginning; follow it and you cannot see its end.
Grasp the ancient Dao to master the present existence.
To be able to know the primordial beginning, this is called the thread of the Dao.