What is the importance of Thoreau's transcendentalism perspective?

Henry David Thoreau's perspective on Transcendentalism was one that emphasized two main themes of this movement.
The first aspect of Thoreau's worldview (as expressed through his writings) was his belief in the individual conscience. Thoreau, as he suggested in "Civil Disobedience," believed that a person was bound by their conscience in all things and was justified in disobeying laws that ran contrary to his conscience. The state, though its actions were ostensibly based on the will of the majority, had no control over the soul of the citizen. As Thoreau argued:

There will never be a really free and enlightened State until the State comes to recognize the individual as a higher and independent power, from which all its own power and authority are derived, and treats him accordingly.

This emphasis on the individual and his conscience was fundamental to the transcendentalist movement. It is also perhaps the aspect of his thought that had the broadest importance and significance in American life, because it inspired movements based on civil disobedience.
The second aspect of Thoreau's thought that was most consistent with fellow transcendentalists was his emphasis on nature. Thoreau saw modern life (in the midst of extraordinary technological and economic change) as corrupting, and he looked to nature as a pure expression of the divine. This was part of the reason he moved to Walden, separating himself to some extent from what he saw as the crass commercialism of society. While few transcendentalists took the path Thoreau did, the belief that God was seen through nature was a powerful belief among his contemporaries.
http://thoreau.library.ucsb.edu/thoreau_life.html