In "Sonnet 12" by Shakespeare, how does he show the passing of time in the poem?

A key theme in Shakespeare's sonnets is the passing of
time and its inevitable impact on the beauty of the person addressed in these poems. The
speaker seems concerned and deeply saddened by the many different reminders of the
inexorable nature of the passing of time, which leads him to consider how the beauty of
his beloved will likewise fade and diminish, just as in this poem he beholds "the violet
past prime" and the "sable curls all silver'd o'er with white." The changing of the
seasons as we move from summer into fall indicates the symbolic "death" of the beauty of
nature. You might want to consider the images of death that we are presented with: the
trees that are "barren of leaves" and the "brave day sunk in hideous night." References
to time emphasise the way that all things die and pass into blackness, which of course
makes the speaker realise that his beloved to "among the wastes of time must go." The
only defence mankind has in the face of death is to procreate, and therefore create
images of ourselves that can stand against time a little
longer:

And
nothing 'gainst Time's scythe can make defence
Save breed, to brave him when
he takes thee hence.