With Sonnet 140, William Shakespeare at first seems to set out on some general counsel for his mistress not to try his patience too much, as doing so might drive him mad and cause him, in his madness, to say bad things about her. The damage this could do would be exacerbated by a world that is itself full of mad people who would be inclined to believe him even if what he came out with were but scurrilous lies.

Strongly implied also though is that not everything scandalous he might say about his mistress would necessarily be untrue, And with the last line of the closing couplet, he then ties his sonnet firmly back to the previous one and reiterates his request that even though she obviously has other lovers, she keep her eyes on him when they are together at least.