William Shakespeare, Sonnet CXVI: "Let me not to the marriage of true minds"
Prose paraphrase: Let me raise no objections to a union created by true love. True love does not change simply because temptation arises, nor easily gives in to the tempter. Oh no! True love is like a lighthouse that watches storms but does not fall to them. It is Polaris (the North Star) guiding sailing merchant ships whose value isn't known but whose size is easily seen. True love is undying, though the physical aspects (beauty, etc.) fade with passing time. It does not change in hours or weeks, but endures until the end of life. If I am wrong, and proved to be so, then I recant all my writing and no man has ever truly loved.
Rhetoric: At the level of the poem's speaker, it could be construed that a man is speaking to a male friend about the most ideal form of love perhaps to reassure his friend of the security and reliability of his friends' relationship. I have always gotten the sense from this sonnet that the fictional speaker was sitting with a male friend, earnestly leaned forward and passionately stating his case that his friend has nothing to worry about as his relationship is clearly one of true love, so no other temptations (e.g. the social position that his girlfriend might find if she were to try to snag a spouse of higher nobility) can get in the way. By praising the strength of a true love relationship—it's never-changing constancy and 'guiding light' properties—the speaker appeals to his friends emotions with bold, heartening words that are equal parts soothing, supporting and encouraging. At the level of the writer, it has always seemed to me that Shakespeare was perhaps speaking to a benefactor similarly to how the fictional speaker of the sonnet spoke to a friend: reassuring him that true love is unchanging in an effort to soothe perhaps understandable concerns regarding whether or not the other man's love interest would remain true in King James...