Emily Dickinson turns a landscape into a household. In eight lines, a mountain becomes a patriarch seated in his armchair, and the seasons and days become his descendants. The central idea is a contrast of scales. Next to a mountain, time looks like a game played by children. Winter, spring and summer come and go, but the thing they circle around does not move.
The first stanza gives the mountain authority. Its verb is simply "sat," a deadpan choice, as if sitting were a decision it had once made and never revised. The "Plain" below it works like a floor or a courtroom. The "tremendous Chair" is funny in its sheer size, but "tremendous" also keeps some of its older force, something that makes you tremble. Dickinson then loads the mountain with vocabulary from the world of officials. "Omnifold" is an unusual, Latinate coinage that suggests seeing in every direction and in many ways at once. "Inquest" is a legal word for a formal inquiry, so the mountain is a judge or investigator whose gaze never stops: "His inquest, everywhere." What a mountain does is look out over everything below it, and Dickinson makes that look sound like a lifetime's work.
The second stanza softens the mood. The "Seasons played around his knees / Like Children round a sire," and the awe becomes something nearly affectionate. The simile makes the year's turning small and playful, and it makes the mountain patient. The last two lines are harder to untangle, because the word order is inverted: "Grandfather of the Days is He / Of Dawn, the Ancestor." The most natural reading is that the mountain is the ancestor of Dawn itself, which makes it older than the morning that arrives each day. Days descend from Dawn, and Dawn descends from the mountain. The grammar loops back on itself, as if the poem is reluctant to leave so old a figure and reaches for one more title for him. One could also imagine, from the imagery alone, that a peak catches the first light, but the poem never says so. It gives the family tree and leaves the reason unstated.
The form suits this mix of grandeur and warmth. The stanzas alternate eight-syllable and six-syllable lines, the pattern of common meter, which will be familiar to anyone who knows hymns and ballads. The effect is a plain, steady, almost sing-song movement. In "The Mountain sat upon the Plain" the beat is calm and even, as if the line itself were sitting still. The rhymes are loose. "Chair" and "everywhere" rhyme properly, but "Plain" and "omnifold" do not rhyme at all, and "sire" and "Ancestor" share little more than a final *r* sound. The near-misses keep the poem from sounding too tidy, a little as though the mountain could not be fully fitted into a nursery-rhyme pattern. Dickinson's capital letters do similar work. "Mountain," "Plain," "Chair," "Seasons," "Children," "Days" and "Dawn" all look like names, so the poem reads like a cast list, and the dashes at the ends of lines 4 and 2 leave a short pause where the reader can picture the scene.
What makes the poem worth reading is how much it does in so little space. It makes geological time easy to grasp by changing its size to a family's. A mountain is almost impossible to imagine as old, but a grandfather in a chair is easy. By putting the seasons at his knees, the poem also suggests that the cycles we think of as vast are only the restless young things around something much older. It is a short piece, and its humor, a mountain wearing the dignity of a judge and the patience of a grandparent, is what lets it carry so large an idea without becoming solemn.