thoreau on ecopoetics

From The Journal, 1837-1861, Henry David Thoreau, page 9:

The poem is drawn out from under the feet of the poet, his whole weight has rested on this ground.

Online sources like Wikiquote continue with the sentence “It has a logic more severe than the logician’s.” But I like better the mysterious sentence that follows in the abridgement I am reading:

Its eccentric and unexplored orbit embraces the system.

What is the orbit?
What is the system?

Also love this amusing (though still mysteriously abridged) fragment from page 14:

Jan. 10. A perfectly healthy sentence is extremely rare. Sometimes I read one which was written while the world went round, while grass grew and water ran.

Did he consider that one healthy or not?