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:
- the yellowing leaves
- the day fading in the west after sunset and black night coming
- the glowing of the fire of life being consumed by ashes