That time of year thou mayst in me behold
when yellow leaves, or none, or few, do hang
upon those boughs which shake against the cold,
bare ruin'd choirs, where late the sweet birds sang.
in me thou see'st the twilight of such day
as after sunset fadeth in the west,
which by and by black night doth take away,
death's second self, that seals up all in rest.
in me thou see'st the glowing of such fire
that on the ashes of his youth doth lie,
as the death-bed whereon it must expire,
consum'd with that which it was nourish'd by.
this thou perceivest, which makes thy love more strong
to love that well which thou must leave ere long.

the sound device used in these lines is

alliteration that provides a musical quality to the poem
a rhyme scheme that sets these lines apart at the conclusion of the poem
a rhythm and meter that emphasizes a change in this part of the poem
onomatopoeia to add a memorable effect at the end of the poem