And I am dumb to tell the crooked rose
My youth is bent by the same wintry fever.
The force that drives the water through the rocks
Drives my red blood; that dries the mouthing streams
Turns mine to wax.
And I am dumb to mouth unto my veins
How at the mountain spring the same mouth sucks.
The hand that whirls the water in the pool
Stirs the quicksand; that ropes the blowing wind
Hauls my shroud sail.
And I am dumb to tell the hanging man
How of my clay is made the hangman's lime.
The lips of time leech to the fountain head;
Love drips and gathers, but the fallen blood
Shall calm her sores.
And I am dumb to tell a weather's wind
Finally “The force” is revealed: it is in fact Time. And not only does Time  have hands , they also have lips. 
 This means they have a mouth, the same way  the speaker and wildlife does , thus connecting all three elements together.
The Force That through the Green Fuse Drives the Flower