Answer:
He describes the sequence between life and death through elements of nature that happen in cycles, having their beginning and end determined, such as life and youth.
Explanation:
Sonnet 73 presents several metaphors about the end of youth and the arrival of old age, these metaphors present elements of nature such as fire, autumn, the presence of birds, among others.
In the first block of the sonnet, we can see that the speaker tries to explain the end of youth, like the end of the seasons, the speaker specifies autumn in this block, showing that in the end of his youth, he can see his own life as a tree without leaves , cold and without birds. At this point, the speaker shows that at the end of his youth, his body no longer has a glow and grace.
In the second block, we can see another element of nature, the twilight. In this block, the author affirms that the end of youth is like the moment when the sun disappears in the west, taking all the light and giving way to darkness, but once, presenting the end of youth, as something dull and discouraging . This is repeated in the third block, when the speaker compares the end of youth with the bright remnants of a fire, which went out and left only ashes.
In these three blocks, we can see that the speaker shows that life is a cycle, since all the elements of nature that he presented end to initiate another element, as well as youth, which ends to initiate old age.
