There are many differences between Shakespeare's and Petrarch's sonnets, the most obvious one being the form of the sonnet. Shakespeare's sonnets have 14 lines, divided into 3 quatrains (a stanza of 4 lines) and a couplet at the end (a stanza of two lines), and they are written in blank verse, meaning that there is no rhyme. On the other hand, Petrarch's sonnets consist of an octave (a stanza of 8 lines) and a sestet (a stanza of 6 lines) and they rhyme.
When it comes to sonnet 130 in particular ("My mistress's eyes are nothing like the sun"), the answer is quite obvious. This sonnet is very unconventional in a sense that Shakespeare seems to write about his loved one in an awful manner, pointing out to her bad qualities, depicting her as an ugly and unattractive woman. But the point is that he loves her nevertheless. On the other hand, Petrarch always talks about his loved Laura in the most beautiful manner. <span />
<span>Shakespeare's sonnet is written to poke fun at the romantic cliches. It is not an idealistic poem, and is a bit of a satire on the Petrarchan love poetry model in itself. In comparisons about the woman's voice and appearance, he is less than perfectly complimentary.</span>
i dont think there is any reason. you might find that the author has the same themes that he/she likes to write about but idk i think you need to read the book
