Henry David Thoreau was a Transcendentalist. He believed in both the power of nature and the power of the individual. These ideas can be seen in one of his most famous works, Walden.
We must learn to reawaken and keep ourselves awake, not by mechanical aids, but by an infinite expectation of the dawn, which does not forsake us in our soundest sleep.
Here, Thoreau speaks of the power of nature. It is through nature's power that we, as human beings, are able to become spirituality awake (transcend human limitations). Through nature, we learn to elevate our lives through a "conscious endeavor" with nature itself. Thoreau speaks of his desire to no longer live like the "ant" ("meanly"), "fritted away by detail." What he means by this is that the ant lives in the details of life only. It is only when we, mankind, turn away from the "details" of life that we are actually able to live.
"Simplicity, simplicity, simplicity" is Thoreau's mantra. By living simply, one is able to pay far more attention to the nature around oneself. By engrossing oneself in nature, one is able to succeed in life. Thoreau was able to do this by moving to a small cabin in the woods. This change in lifestyle and pace of life allowed him to simplify and to pay attention to the most important things in life, changing the "atmosphere and medium" through which we look at life. By simplifying life, Thoreau was able to pay attention to only the "essential facts of life."
Therefore, Thoreau looked at Transcendentalism as a way of life. Through Transcendentalism, one (he) is able to depend upon one's own individualism and imagination to transcend one's own accepted limitations. By depending upon one's self, as Thoreau illustrates in Walden, one is able to find one's own wisdom, not the wisdom of the multitudes (because what works for one does not necessarily work for another).