“I felt a Funeral, in my Brain"
One of the more striking features of this opening line, and of the poem as a whole, is Dickinson’s consistent use of an insistently literal or physical register, in terms of diction, in a context that renders it fundamentally metaphorical and abstract. The choice of the word “Brain” in this first line (vs the later appearance of “Mind”) is just one example.
One reading of this poetic approach is that Dickinson intends to parse out two “levels” of experience, so to speak, that normally we’d tend to take together as equally psychological and/or allegorical. The concrete imagery of the “Funeral”—complete with Mourners, “A Service, like a Drum,” and the attendant noises and activities of the ceremony—apparently occurring in the speaker’s (physical) “Brain” implicitly contrasts this experience with the thoughts, feelings, and reactions that take place in her “Mind.”
"Then Space - began to toll, // As all the Heavens were a Bell, / And Being, but an Ear"
This is the stage of the poem where Dickinson more or less explicitly takes up the difficult philosophical questions that constitute its central subject. Differences in particular interpretations aside, it’s clear that the metaphorical “Funeral” of the poem’s first half is meant to mark the death of something—perhaps the speaker, some part of her, or some form of relating to or perceiving the world. It is this “death” that occasions the reflections of the poem’s latter half.
It’s also clear that the vision laid out in these lines is, at least on its face, rather bleak. The speaker appears to conclude that our very essence (our “Being”), can only hear the “Bell” of the “Heavens”—never speak it or share it. The speaker’s “I” finds itself kin only to “Silence,” together forming “some strange Race,” stranded, alone, “here”—i.e, in this world. It’s the philosophical impasse at which the speaker finds herself in these lines that sets up the “climax,” so to speak, in the final stanza.
"And then a Plank in Reason, broke, / And I dropped down, and down - / And hit a World, at every plunge, / And Finished knowing - then -"
The first line (and, to some extent, the second as well) of this final stanza is an excellent example of Dickinson’s brilliant and highly idiosyncratic use of the comma. It simultaneously echoes the sense of that line in its form, enacting the rupture of “broke” in the jarring, unexpected caesura, and sets up the tension between form and content that she carries through to the end of the poem. Though on a purely semantic level, the poem seems to speed up, so to speak, here—the imagery of a fall, the repetition in “down, and down,” the use of emphatic diction such as “plunge”—throughout the stanza Dickinson employs caesura (a pause within, rather than at the end of, a line) at key moments.
This device functions to slow down our reading of this portion of the poem overall. Dickinson has also chosen to insert these pauses in places where they are at odds with the syntax of the line (the commas in the first and second lines, as well as the dashes around the last word of the poem, “then,” all fit this pattern). Thus we encounter these pauses as unexpected, jarring, as though the line has suddenly screeched to a halt. The choppy, disjointed quality of this section of the poem cuts against reading it, as we might initially want to, as a description of some kind of epiphany. It introduces an undeniable feeling of ambivalence, which is realized in the ambiguity signaled by Dickinson’s bracketing of the last word of the poem with dashes.
Are we meant to understand that the speaker finished knowing “then”—i.e., at that time, from which she is now presumably removed? Or is it rather another rupture, a thought left incomplete, as in the sense of “then” as a preposition denoting either a temporal or logical sequence? Here the pair of dashes might be understood as creating a “space” for this ambiguity, leaving room for the poem, up until the very end, to hold a multitude of meanings.