Its upper part is not bright, and its lower part
Books:
THE TAO AND ITS CHARACTERISTICS
Its upper part is not bright, and its lower part is not obscure
Ceaseless in its action, it yet cannot be named, and then it again
returns and becomes nothing This is called the Form of the Formless,
and the Semblance of the Invisible; this is called the Fleeting and
Indeterminable