Water
Laozi thought water was the most humble, and its humbleness the most powerful thing in the world.
Really, water has no colour, no taste, no form, thus it can take any form, reflect anything, be responsive to everything.
In water, there is place for everything, looking at water, you see the sky, the trees, the sun and the stars.
But you can also see yourself.
Looking at water is a kind of a meditation, an encounter with yourself, with your emotions, thoughts, your past and present.
All this is in yourselves: the sky, the clouds, the trees and the grasses swaying in the wind.
The water, its ripples and waves are in yourself too.