Answer: The beauty of nature causes the author's "perfect exhilaration."
Step-by-step explanation:
The Nature is Ralph Waldo Emerson's essay about the appreciation of nature, written from a transcendentalist point of view.
In lines 1-20, the author explains his experience upon seeing a wide, open space of "bare" ground. He simply appreciates the beauty of nature he sees, which enables him to clear his mind. As he describes it, he becomes ''nothing'', and is unified with nature. He does not have any thoughts on his mind, and becomes "a part or particle of a God."