Sonnet 7, by NY Shakespeare Exchange

Lo! in the orient when the gracious light
Lifts up his burning head, each under eye
Doth homage to his new-appearing sight,
Serving with looks his sacred majesty;
And having climbed the steep-up heavenly hill,
Resembling strong youth in his middle age,
Yet mortal looks adore his beauty still,
Attending on his golden pilgrimage:
But when from highmost pitch, with weary car,
Like feeble age, he reeleth from the day,
The eyes, 'fore duteous, now converted are
From his low tract, and look another way:
     So thou, thyself outgoing in thy noon
     Unlooked on diest unless thou get a son.

Sonnet 7, from The Sonnet Project, by the New York Shakespeare Exchange.

It's a very curious sonnet.  What happens in a given day is a lifetime.  From a coming of age, to a reeling from all that age.  But what sustains us, literally, is our progeny.  Our progeny comes only from a relationship, without which we do not simply die: We cease to exist.