Shelley begins with a man who refuses to cry. "Mine eyes were dim with tears unshed; / Yes, I was firm," he says, and the quick "Yes" sounds almost defensive, as if he is admitting a stubbornness he now regrets. He is so intent on holding himself together that he cannot look at the woman beside him, and he never guesses how anxiously her glance was "seeking to shine / With soothing pity" on him. The poem is built on that missed connection. Its central idea is that suffering kept private is a prison, and that the way out is open tenderness between two people, which the poem ends up pleading for.
The second stanza turns that silence into a physical image. The soul's "mute rage" "preys upon itself alone," so the pain feeds on the person carrying it. Life becomes "the cage / Of fettered grief that dares not groan," and the stacked words (cage, fettered, dares not) make the grief feel locked up and guarded. Even the rhyme of "eye" with "agony" in the stanza's closing couplet is loose and slightly strained, and that seems fitting, since the sufferer hides his "scorned load" from "many a careless eye."
Relief comes in the third and fourth stanzas. The syntax of the third is tangled, and in this text one line is left with a gap ("The ... thou alone should be"), so the argument is hard to follow. The sense that comes through is that years of torment are repaid by a single moment of kindness "when none were near." The speaker says he woke "from torture for that moment's sake." Then the language softens. Her "accents sweet / Of peace and pity fell like dew / On flowers half dead," a simile that makes her voice a natural, quiet kind of rescue. Her lips meet his "tremblingly," and her eyes "threw / Their soft persuasion on my brain, / Charming away its dream of pain." Calling pain a dream and her gaze a charm, a kind of gentle spell, shows how easily her tenderness dissolves what felt like a cage.
The fifth stanza changes the poem's mood and tense. After remembering, the speaker states the present: "We are not happy, sweet! our state / Is strange and full of doubt and fear." The poem never says what the trouble is, and I won't guess. What matters is the remedy he proposes: "More need of words that ills abate." Having once been unable to speak, he now insists on speech, and he fears "Reserve or censure" more than the hardship itself. The phrase "sacred friendship" raises the relationship to something close to religious, and the word "solace" shows what is at stake, since without this bond "No solace left for thee and me."
The last stanza makes the plea personal. He does not want her to become "Aught but thyself," and above all not to "stoop to wear / The mask of scorn, although it be / To hide the love thou feel'st for me." The ending is moving because it turns the opening on its head. At first he was the one hiding behind firmness, and now he begs her not to do the same. He has learned what concealment costs, and he does not want her to pay it too.
The form suits this intimacy. Each of the six stanzas is a sestet of short, mostly iambic lines of eight syllables, rhymed ababcc, so every stanza ends on a couplet that settles like a conclusion. The couplets often carry the emotional point, as with "shine / mine" at the start and "be / me" at the close, and the plain words "me" and "thee" keep the poem close to speech. There is little of the soaring abstraction readers expect from Shelley. The vocabulary is simple, and the feeling comes from the contrast between "mute" and "words," and between cage and dew.
The poem is also interesting for who it is addressed to. Its title uses the name she bore before she became Mary Shelley, which suggests it belongs to an earlier stage of their relationship. Whatever its exact occasion, its lasting appeal is that it makes a private moment of comfort feel universal, and that it argues for honesty in love by showing the loneliness of its absence.