How we cite our quotes: The poem is 159 lines long, so we just cite by line number.
Quote #4
feelings too
Of unremembered pleasure (30-1)
Remembering the "beauteous forms" of the Wye valley doesn't just conjure up memories of that particular nature walk. It helps remind the speaker of all the seemingly trivial "acts/ Of kindness" (34-5) that he's committed in his life.
Quote #5
And now, with gleams of half-extinguished thought,
With many recognitions dim and faint,
And somewhat of a sad perplexity,
The picture of the mind revives again: (58-61)
Now that the speaker is back at the Wye again, he's "perplexed," or confused, at the disparity between what he remembers, and what he sees. His memory, which was so immediate during the "five long winters," has become "half-extinguished thought."
Quote #6
when thy mind
Shall be a mansion for all lovely forms,
Thy memory be as a dwelling-place
For all sweet sounds and harmonies (139-142)
The speaker imagines Dorothy's mind and memory using house metaphors. Her mind will be a "mansion," and her memory a "dwelling-place" for all the beautiful things she sees and hears on this trip to the Wye valley. Then, in future years, if she's unhappy, she'll be able to revisit this mental "mansion" and see it all again in her mind's eye.