It seems in the octet as if Shakespeare is undermining love - that it is only something frivolous, until in the Heroic couplet when he offers a completely different view on love, one in which superficialities are meaningless. Keeping in mind the images and ideas presented to us initially and vaguely in the octet, the sestet puts into words the argument that Shakespeare had silently been developing up till now. Of particular interest in the sestet is the section that compares his mistress with a goddess - "I grant I never saw a goddess go; My mistress, when she walks, treads on the ground." This suggests to us that his mistress is completely human, and hints at the idea that some of the normal comparisons are unrealistic. The heroic couplet, the last two lines of the sestet, clinch the entire poem's argument. He declares that the love for his mistress is "as rare" as any other woman whose beauty has been exaggerated with "false compare". The use of the octet - to present the opposing argument; the sestet - to present the author's argument; and the heroic couplet - to clinch the final argument all contribute towards developing the meaning of Sonnet 130.
There are a variety of language techniques employed by Shakespeare to emphasise his argument. The most obvious of these is the interesting choice of words. For example, the use of "roses" in the comparison between roses and his mistress" cheeks. Rose petals are soft, almost silky to the touch, pleasant to look at and have perfect shades of colour. Shakespeare uses the word to conjure up several different images and create several different effects. Just from the use of one word, he says that his mistress" cheeks are not soft, nor do they own the colour of roses - just like all of her other features, they are plain and not worth noting. By using the example of a "goddess" in comparison to his mistress, the author again heightens the effect of the poem.