The use of imagery and figurative language in poetry can be used to add complexity and depth to the plot and overall tone of a poem. Often times an author will incorporate poetic devices in order to stimulate the senses of the reader in a nuanced manner that further enhances the message or theme of the poem. Similarly in Sonnet 12, Shakespeare's use of poetic devices is used in conjunction with the actual words to enhance the idea of the passage of time. Starting from the title (the number "12") the reader is already exposed to the complex way in which the author alludes to time. Furthermore the use of imagery and figurative language is used to help give the reader a clearer understanding of the author's own emotions and psychological conflicts with the passage of time. .
It is effortless to deduct from reading of the poem that the passage of time is a major theme in this poem. Shakespeare talks about the swift passage of time and its crippling ability on all things. What is interesting to notice however is that in the very beginning of the poem he states, "When I do count the clock that tells the time" (line 1). The author incorporates alliteration in the last four words of the first line; "that", "tells", "the" and, "time". All four letters begin with the letter "T", and when read out loud can be argued to sound exactly like the ticking of a clock, which in other words represent to the reader the passage of time. What is further interesting is that the author used the word "clock" within the same line and is actually talking about the passing of time. By this use of alteration the author is able to add depth in the poem and create complexity. .
Through the use of imagery the author seeks to juxtapose different themes, and give the reader a clearer understanding of the authors position with respect to these themes.