To realize that you do not understand is a virtue; not to realize that you do not understand is a defect. - Laozi

Because the eye gazes but can catch no glimpse of it,
It is called elusive.
Because the ear listens but cannot hear it,
It is called the rarefied.
Because the hand feels for it but cannot find it,
It is called the infinitesimal.
These three, because they cannot be further scrutinized,
Blend into one,
Its rising brings no light;
Its sinking, no darkness.
Endless the series of things without name
On the way back to where there is nothing.
They are called shapeless shapes;
Forms without form;
Are called vague semblance.
Go towards them, and you can see no front;
Go after them, and you see no rear.
Yet by seizing on the Way that was
You can ride the things that are now.
For to know what once there was, in the Beginning,
This is called the essence of the Way.

Water is fluid, soft & yielding but water will wear away rock, which is rigid and cannot yield ... what is soft is strong.

The excellence of water appears in its benefiting all things, and in its occupying, without striving (to the contrary), the low place which all men dislike.