Dickinson's speaker begins with a hypothetical: suppose I am lost, suppose the door has now closed. Even so, she insists, the delight of having once been found will stay with her. The poem opens as a defense of memory. A moment of grace, however brief, can't be undone by what comes after. But the poem doesn't remain consoled. Its second half turns hurt, then sharp, and ends with a warning aimed at someone called "Sir."
The first stanza is about brightness and speed. The "Jasper Gates" "Blazed open -- suddenly," and the verb does the work: a gate that blazes is lit from within, and the adverb arrives only after a dash, as if the speaker is still catching her breath. Jasper recalls the heavenly city of the Book of Revelation, whose wall is described as jasper, so the setting is unmistakably the Christian heaven. The word "transport" is worth pausing on. It means ecstasy, being carried out of yourself. But it also means being carried away from a place, which anticipates the "banished" of the second stanza. Her joy and her exile are both forms of being moved.
The second stanza shifts from light to touch. The speaker's face is "awkward -- gazing," the face of someone gawping at a miracle with no idea how to arrange her features. The angels "softly peered," a lovely, slightly comic image, like neighbors looking over a fence at a visitor. Then they "touched me with their fleeces." Fleeces are an unexpected detail. They suggest lambs, and so perhaps the shepherd imagery of the Savior, but the effect is mostly physical: warmth, wool, softness against skin. Then comes the crack in the poem's tone: "Almost as if they cared." That "Almost" is the hinge. She remembers the tenderness, but she can no longer be sure it was real, and the doubt is the wound.
After this the language turns flat and legal. "I'm banished -- now -- you know it" states her situation as a fact, with no "if" left. Then comes the understated line "How foreign that can be." Foreign is a strange word for exile from heaven. It makes banishment sound like waking up in a country where you don't speak the language, and it suggests she once felt at home. The last lines swing the poem outward. "You'll know -- Sir -- when the Savior's face / Turns so -- away from you." The "so," set off by dashes, almost enacts the gesture, a face turning aside. The poem never says who "Sir" is. Judging by the tone, he could be someone who has judged her, but that is an inference, and the poem leaves him unexplained. What matters is the reversal. The person who seems secure will one day feel exactly what she feels.
The form fits this unsteadiness. Line lengths wobble: the first stanza runs roughly four, four, six, eight and six syllables. The longer-then-shorter lines faintly recall a hymn, but the pattern keeps slipping. Rhyme is thin and arrives late. "Be" and "suddenly" only echo each other, and "be" returns at the end of a later line to chime loosely with "you." The one clean rhyme, "peered" and "cared," lands in the middle of the second stanza, on the tenderest and most doubtful moment. The dashes, so typical of Dickinson, work as hesitations and stammers, and they stop the lines from ever sounding like a confident sermon. The capitals on Angels, Gates and Savior give the sacred things a hard outline against that nervousness.
What makes the poem significant is how it handles faith. It doesn't treat salvation as a certificate you either hold or don't. It treats it as an experience that can be remembered, doubted and lost, and its "If" gives way to a flat "I'm banished." It also refuses a tidy ending. There is no reconciliation, only an image of a turned face. For a reader, the strongest effect is that the speaker's gratitude and her anger are both real, and the poem lets them sit side by side.