In just thirty-two words, Dickinson builds a character and then lets the air out of her. The woman in this poem has a spirit that has "rose to such a height" that her face swells, her manner turns superior, and she gives off a scorn that others would do well to avoid. The central idea seems to be that loftiness, once it becomes a performance, curdles into contempt. The poem never says she is wrong to feel elevated. It simply shows what that elevation looks like from the ground, and the view is not flattering.
The vocabulary does much of this work. "Spirit" is a grand, serious word, but the verbs attached to it soon go physical. Her spirit "rose," her countenance "did inflate," and her scorn "effervesced." Rising, inflating and fizzing all involve air or gas, so the poem quietly turns a soul into a balloon, or a bottle of something sparkling. "Countenance" is a stiff, formal word for a face, and the awkward construction "Her countenance it did inflate" doubles the subject and adds an old-fashioned "did," as if the line were mimicking a pompous sermon. The simile that follows, "Like one that fed on awe," is carefully worded. The speaker doesn't claim she lives on other people's admiration, only that she looks like someone who does. Awe becomes food, and the face puffs up as if well fed. The judgement is about appearances, which is exactly what makes it sting.
The second half shifts from description to warning. "More prudent to assault the dawn" is a deliberately absurd piece of advice. Attacking the sunrise is hopeless, since dawn is vast, impersonal and certain to arrive, yet the speaker calls it the safer option. That exaggeration is where the humour lies, but it is also where the threat sits, because a person whose scorn is worse than a doomed attack on daybreak is formidable. "Merit" is a dry choice of word. We usually merit rewards, and here one can "merit" scorn the way one earns a wage. The scorn is also "ethereal," a word that suggests the heavens, the upper air and something too refined to touch. It comes from above, and the lowly can only look up at it. Then comes "effervesced," from a Latin root meaning to boil over. It makes the scorn sound sparkling and light, and also frothy and mostly air. Since bubbles rise, the word may quietly echo "rose" from line one, so that the poem ends where it began, with something lifting upward and being not quite solid.
The shape of the poem supports this. It falls into two matching triplets, each running two longer lines of about eight syllables and then a shorter one of six: "Like one that fed on awe" and "That effervesced from her." The short lines land like small drops after a rise. The rhymes are loose. "Height" and "inflate" are a near-rhyme, while "dawn" and "scorn" chime more fully. Line 3 ends on "awe," which shares its vowel with "dawn" and "scorn," so the sound of wonder seems to curdle into the sound of contempt across the poem. The final word, "her," rhymes with nothing. The person at the centre is left isolated at the end, which suits her. The steady beat is almost hymn-like, and that solemn music makes the mockery sharper, because the poem sounds reverent while pricking its subject.
What makes the poem worth reading is how much it suggests in such a small space. Dickinson, who lived from 1830 to 1886, is known for compression, and here a portrait, a joke and a moral all fit into six lines. The poem also leaves the speaker's attitude open. Is the tone amused, admiring, or a little afraid? I'd argue it is all three, and that this mix is the point. We laugh at the inflated face and the absurd advice, yet the final image of scorn drifting down from a great height is oddly chilling. For a student, the poem is a useful lesson in how word choice alone, without any explanation, can turn praise into satire.