The Prelude: Stealing the Boat by William Wordsworth

This quote appears in the opening lines:

It was an act of stealth / And troubled pleasure

☆ "Stealth" establishes the poem's moral ambiguity - it suggests secrecy, wrongdoing, and transgression.
☆ The following line provides us with the oxymoron "troubled pleasure", indicating the thrill of the action, but also the inner resentment that he holds.
☆ To a broader extent, "Stealth" foreshadows the darker turns in the poem as Wordsworth becomes overwhelmed by the power of nature.

This quote appears in the later lines when Wordsworth becomes awestruck by the mountains:

a huge peak, black and huge

☆ The repetition of the adjective "huge" suggests that Wordsworth was too shocked to find words to articulate his feelings.
☆ Additionally, it could also emphasise how the mountain dominates and intimidates him.
☆ If we look further into the line, the "black" that separates the two "huge"s adds a more sinister tone to the mountain, as black is often connoted with mysteriousness, and a sense of foreboding which Wordsworth experiences in that moment.

Towards the very end of the extract, Wordsworth says this:

There was a darkness – call it solitude, / Or blank desertion

☆ Both "solitude" and "blank desertion" reflect that Wordsworth is aware of his limitations; of his loneliness. He feels "desert[ed]" by the overwhelming nature.
☆ "Darkness" relates to the "solitude" that Wordsworth experiences, by emphasising the void that the power of nature instills.