How we cite our quotes: (Essay.Paragraph)
Quote #10
We are conscious of an animal in us, which awakens in proportion as our higher nature slumbers. It is reptile and sensual, and perhaps cannot be wholly expelled; like the worms which, even in life and health, occupy our bodies. (Higher Laws.11)
While most of the time "nature" stands for all that is good in the world, there are times, such as this, when Thoreau speaks of our animal nature in negative terms.
Quote #11
This was his looning, -- perhaps the wildest sound that is ever heard here, making the woods ring far and wide. I concluded that he laughed in derision of my efforts, confident of his own resources. (Brute Neighbors.17)
Thoreau often personifies animals as well. Here, Thoreau gets out-witted by a loon. Before you laugh, try and catch one yourself.
Quote #12
I would that our farmers when they cut down a forest felt some of that awe which the old Romans did when they came to thin, or let light to, a consecrated grove, (lucum conlucare) that is, would believe that it is sacred to some god. (House-Warming.13)
According to Thoreau, we should conserve nature because it is sacred and necessary to humanity. Nature isn't something to be used irresponsibly. It seems that, at a point in history, humans were aware of this, but we've since lost that lovin' feeling.