What you look at but cannot see is called the invisible;
What you listen to but cannot hear is called the inaudible;
What you touch but cannot hold is called the intangible.
These three are undefinable.
Thus, they are joined as one.
From above it is not bright;
From below it is not dark;
It is so vague as to defy description;
It reverts to a state of nothingness.
This is called the form that has no form,
The image that has no substance;
This is called the indistinct and indistinguishable.
Facing it, you cannot see its front;
Following it, you cannot see its rear.
Hold fast to the ancient Dao to master the here and now.
The ability to know the beginnings of antiquity,
This is called the essence of the Dao.
Mere words are insufficient to explain the subtle and profound mystery of the way, no matter how elegantly and eruditely they are combined in each other.
Rather than losing yourself in the pursuit of its complexity, better to take a step back and contemplate its simplicity: a single unbroken thread that stretches from the very dawn of antiquity and provides the key for understanding the present day.