What is the theme of Sonnet 73?William Shakespeare

The theme of William Shakespeare's Sonnet
73 is the importance of the friend of the poet's loving him more strongly
because of the temporal state of life.  Calling attention to his aging in order to
convince his lover of the urgency of full affection, the poet uses images such as
"yellow leaves" and "twilight."  And, with the prefix twi-- which
means "half," the poet suggests that his life is nearing its completion.  As the sonnet
develops, the suggestion of death comes in the second
quatrain:

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.

Further, the
ending couplet summarizes the purpose of this sonnet; that is, the poet pleas with his
lover to love him more strongly since there is so little time left to
him.

In summary, the theme of the importance of the lover
devoting attention to the poet is expressed in three
metaphors:

1. the yellowing
   leaves


2. the day fading in the west after sunset and black
   night coming


3. the glowing of the fire of
   life being consumed by
   ashes