What are some examples of how imagery in "Lines Composed a Few Miles Above Tintern Abbey" enrich the theme of the power of nature to heal and nuture the human spirit?
As you write in your question, one of the themes of Wordsworth's "Lines Composed a Few Miles above Tintern Abbey" is that nature has the power to heal and nurture the human spirit.
The poem begins with the narrator looking at a beautiful rural landscape. Among the images he sees are:
*"steep and lofty cliffs"
*"dark sycamore [trees]...
plots of cottage ground...orchard tufts,
Which at this season, with their unripe fruits,
Are clad in one green hue, and lose themselves
'Mid groves and copses"
*hedgerows, hardly hedgerows, little lines
Of sportive wood run wild; these pastoral farms,
Green to the very door"
In the second stanza, the narrator describes how he has often used the memories of this scene to heal his soul:
oft, in lonely rooms, and 'mid the din
Of towns and cities, I have owed to them,
In hours of weariness, sensations sweet,
Felt in the blood, and felt along the heart;
And passing even into my purer mind,
With tranquil restoration
Often, when I was in a lonely room, exhausted, and amidst the noise of a town or city, I have thought of this scene and it has brought me sweet feelings of quiet healing; these feelings I felt in my blood and in my heart.