Four short lines, not a single comma, and yet a whole bargain fits inside. A speaker, whom the title names a "Mistress," says that "a rough gentleman / paid me for my heart," then pictures the two of them sitting together in a silence that is both company and isolation. The poem never says what was sold, what it cost, or what the buyer wanted. Its central idea seems to be that closeness can be bought but connection cannot. The nearer the two sit, the more the final image sets a wall between them.
The title is a loaded word. A mistress can be a kept lover, but the word is also the feminine of "master," someone with authority. The poem sets these meanings against each other. The title promises a person with a position, yet in the first sentence the speaker is the object of the verb: someone "paid me." The "rough gentleman" is a small collision of his own. "Gentleman" suggests manners and polish, "rough" suggests friction and force, and the poem never tells us which wins. Then comes the surprise of "heart." We expect a body to be bought, so the substitution is unsettling. It might be a dignifying euphemism, or it might be crueller, a hint that feeling itself has a price. Read literally, a heart is something you cut out and hand over. The line is made of five one-syllable words, "paid me for my heart," and the bluntness is as flat as a receipt.
The second couplet turns from transaction to atmosphere. "We sat alone and not alone" folds back on itself: "alone" appears twice, and the second is cancelled by "not." The word "we" is the only moment the two are joined, and the rest of the line pulls them apart. Then the poem swerves into its strangest move, a simile that refuses to behave. Instead of the expected comparison to strangers on a train or people in a waiting room, we get "like a place to lay a wall." That is a building site, ground marked out before anything exists on it. Nothing is built yet, but the sitting is the preparation. A wall both divides and shelters, which fits the paradox of the line before: two people can share a room and still be on opposite sides of something. The verb "lay" may also carry a faint, uncomfortable echo of the bodily bargain the title hints at. That is an inference, but the poem's compression makes such echoes hard to ignore.
The construction is as spare as the story. The poem is two couplets without rhyme, and "heart" and "wall" do not chime. This feels right, since nothing in the situation is resolved or reconciled. The lines run five syllables, five, then eight and seven, so the second stanza stretches out, as though the sitting lets the silence lengthen. Sound quietly links the two halves. The long "a" of "paid" returns in "place" and "lay," so payment and laying are tied together by echo before we notice. Everything is lowercase and there is no closing full stop, so the poem begins as if mid-scene and ends without announcing itself, leaving the wall unfinished on the page.
What makes the poem worth studying is how much it asks of so little. It does not tell us whether the speaker is a victim, a willing partner, or both, and it does not moralise about the "rough gentleman." It gives one transaction and one odd image and trusts the reader to do the building. Who will lay the wall, and who is already on the far side of it? The simile carries almost the entire weight of the poem, and a reader who stays with it longer will find that it keeps changing meaning.