Poetry help in identifying natural imagery?

[gigi_4ever]

The Waking
~Theodore Roethke

I wake to sleep, and take my waking slow.
I feel my fate in what I cannot fear.
I learn by going where I have to go.

We think by feeling. What is there to know?
I hear my being dance from ear to ear.
I wake to sleep, and take my waking slow.

Of those so close beside me, which are you?
"GOD BLESS THE GROUND! I SHALL WALK SOFTLY THERE,"
And learn by going where I have to go.
"LIGHT TAKES THE TREE; BUT WHO CAN TELL US HOW?"
"THE LOWLY WORM CLIMBS UP A WINDING STAIR;"
I wake to sleep, and take my waking slow.

Great Nature has another thing to do
To you and me, so take the lively air,
And, lovely, learn by going where to go.

This shaking keeps me steady. I should know.
What falls away is always. And is near.
I wake to sleep, and take my waking slow.
I learn by going where I have to go.
Would the capitalized lines by the only natural imagery used in the poem? Are there lines that I missed? If someone could explain the poem, that would be of great help too. I feel that I am not fully grasping the full meaning of the author. Thank you to all who answer in advance.
Also, what is the progression in the imagery?