Shakespeare's sonnet 130 has a simple message of the dark lady's beauty. Her beauty cannot be compared to the beauty of a goddess or to that found in nature because she is only a mortal human being. Shakespeare's sonnet 130 is a comparison to Petrarch, who would write about a beauty of a women like a goddess. Shakespeare said in lines 11-12:
“I grant I never saw a goddess go, my mistress when she walks treads on the ground,” he clearly states that his mistress is no goddess. Shakespeare also says she is not beautiful as things found in the nature like the sun, which is how the sonnet begins.
Above all these things the sonnet says, the narrator loves her nonetheless. In the closing couplet he says that in fact she what he feels for her is rare. You would think he isn't in love, because of the way he described the women with such exaggeration and false comparisons like he has done. That's what makes Shakespeare sonnet 130 unique, because of how blunt and his charming sincerity he made that has become one of the most famous in the sequence.