This is perhaps Shakespeare's best sonnet, technically speaking. What makes it unique is the display of metaphors. Each of the three stanzas contains two metaphors. The first in each case is a metaphor for the speaker's age, and the second is a metaphor for that metaphor.
In the first stanza the poet, presumably Shakespeare himself, compares his aging condition to
That time of year...
When yellow leaves, or none, or few, do hang
Upon those boughs which shake against the cold,
And then he compares those barren boughs to
Bare ruined choirs, where late the sweet birds sang.
The sound of singing birds is simulated by the "S" sounds in "sweet" and "sang." It should be noted that the concept of the boughs shaking because of the cold is a poetic conceit. The boughs cannot not feel the cold but are shaking because of the wind. What is interesting is that they look as if they are shaking because of the cold. And they look as if they are shaking because of the cold because they are nearly naked....
(The entire section contains 716 words.)