"Sonnet 116," often referred to as "Let me not to the marriage of true minds," begins by affirming that genuine love does not acknowledge any obstacles to its existence. The first sentence, "Let me not to the marriage of true minds / Admit impediments," introduces the first metaphor of the poem. The "marriage of true minds" is not a literal wedding but a metaphor for the union of two people's souls in a deep, genuine, and everlasting love. The speaker asserts through this line that true love knows no "impediments."

The third and fourth lines (along with the beginning of their sentence in the second part of line 2) make a powerful statement. According to the speaker, true love remains constant when it encounters change around it. It does not yield or bend when faced with someone attempting to remove it. In other words, genuine love remains fixed and unswerving.

The fifth and sixth lines introduce the metaphor of love as an "ever-fixed mark." This mark is unchanging and unwavering, even during life's greatest storms. It is like a navigational beacon for ships, guiding them safely through treacherous waters. The imagery of the "star to every wand'ring bark" emphasizes love's reliability and guidance.

In the eighth line, the poem acknowledges that the true value of this love may be unknown, even though its existence and significance are evident. Just as a star's worth cannot be measured (though its height above the earth can be calculated), so love's worth is incalculable.

As the sonnet progresses, the poet begins to examine love through time. With the declaration that "Love's not Time's fool," the speaker unequivocally asserts that genuine love remains impervious to the whims and fluctuations of time.

The lines that follow, "though rosy lips and cheeks / Within his bending sickle's compass come," emphasize that while time may lead to the fading of physical beauty, the withering of youth, and the transformation of circumstances, love remains unaltered. In this context, youth is symbolized by "rosy lips and cheeks." The speaker showcases the constancy and steadfastness of authentic love, highlighting that it is not merely a fleeting emotion tied to the temporal world but rather a force that persists regardless of anything.

The thirteenth and fourteenth lines solidify that point: "Love alters not with his brief hours and weeks, / But bears it out even to the edge of doom." As described in this sonnet, true love endures beyond the short-lived experiences of hours and weeks and lasts until the end of human existence, "the edge of doom."

The final couplet is a powerful declaration of the poem's central message. The speaker boldly claims that if he is proven wrong about the power and nature of love, then he has never written a word, and no one has ever truly loved. This statement underscores the speaker's absolute conviction in genuine love's timeless and unchanging nature.