In Wordsworth's “Tintern Abbey," how are his ideas/principles reflected and demonstrated?

Wordsworth (1770–1850) is known as a Romantic poet, which means that much of his poetry celebrates the beauty and power of nature. English Romantic poets of this time saw the industrial revolution, which brought with it cities dominated by factories pumping smoke into the skies, as a threat to the natural landscape.
In "Tintern Abbey," an autobiographical poem published in 1798, Wordsworth returns to the eponymous abbey, in southeast Wales, five years after his previous visit. He comments on how the beautiful landscape around the abbey ("these orchard-tufts . . . groves and copses . . . pastoral farms, / Green to the very door") have impressed themselves upon his memory, and helped him cope with "the din / Of towns and cities." One way in which Wordsworth emphasizes the beauty and serenity of the natural world is to contrast it with the ugliness and noise of the city. For example, he describes the natural world as inspiring in him a "tranquil restoration," and "sensations sweet," but describes life in the city as "the fretful stir" and "the fever of the world."
Wordsworth also uses language, when describing the natural world, which connotes freedom and respite, such as "waters, rolling from their mountain tops," "little lines / Of sportive wood run wild," "the quiet of the sky," and "I again repose . . . under this dark sycamore."
In the second half of the poem, Wordsworth describes how his response to nature has changed since his "boyish days." When he was a boy he used to revel in the aesthetic beauty of nature. He would admire the "colours and the forms" but had no interest "Unborrowed from the eye." In other words, he had no interest in any part of nature that he could not see with the eye. Now that he is older, however, Wordsworth appreciates nature in a more philosophical sense. Nature now, he says, is "the anchor of my purest thoughts, the nurse, / The guide, the guardian of my heart, and soul." This sequence of metaphors suggests that nature steadies him and allows him to be thoughtful and reflective ("the anchor"), and also that it heals him ("the nurse") and tends to the aches he acquires from his time in the city.

In this poem, Wordsworth demonstrates the way in which nature and simple scenes of everyday life can be so affecting and uplifting to the spirit. They have the ability to bring an observer joy, even as a memory; they can make the world feel like a better, kinder place, even to a spirit that is overburdened with cares. The speaker envies the hermit who keeps to the woods because he is free to engage only with what he loves. Being in nature, as such a man is, elevates one's thoughts so that one develops a greater understanding of the sublime. The poem gives voice to Wordsworth's romantic ideas about the importance of nature and the effects that it has on people; further, his own belief that poetry ought to reflect everyday experiences in everyday language is also reflected.