Final answer:
The tone of Shakespeare's Sonnet 130 changes from analytic to witty, with the speaker affectionately concluding that his love is genuine despite not using exaggerated poetic comparisons.
Step-by-step explanation:
In William Shakespeare's Sonnet 130, the tone shifts from being rational or analytic to witty. Initially, the speaker describes his mistress using realistic terms that defy the idealized descriptions common in love poetry of the time. As the poem progresses, the speaker uses a series of negations to humorously subvert traditional poetic comparisons. The true affection is revealed at the conclusion, where the speaker asserts that his love is as rare as any lauded with false comparisons, marking a shift to an affectionate tone.