Lines 1–4
“I felt a Funeral, in my Brain” is a poem in which Dickinson attempts to render into formal poetic language the experience of a mind facing its own collapse; the opening stanza presents the metaphor of a funeral that is used throughout the poem to convey the sense of this breakdown to the reader. Brain here refers to both the concrete physical organ and to the abstract idea of the speaker’s mind; such dual meanings are used throughout the poem to convey the physical and mental effects of the breakdown. Losing one’s reason is like a funeral: the final interment and burial of rational thought. The mourners can be read as symbols of the events or ideas that bring on the speaker’s collapse; such events or ideas are incessant (they keep “treading—treading”) and continue until the speaker begins to realize what is happening. Her “sense” (or knowledge) of what is occurring begins “breaking through” to culminate in some kind of understanding about her impending devastation. Like the word brain, which has two meanings, the word sense can also refer to the speaker’s physical senses, which are likewise affected by the mourners plaguing her mind.

Lines 5–8
As the opening lines set up the funeral as an overall metaphor for the speaker’s breakdown, subsequent stanzas refer to specific parts of the funeral ritual to further convey the speaker’s experience. This stanza dramatizes the speaker’s growing fears and mental instability primarily through the use of sound. The mourners are all seated, representing a quiet moment, perhaps marking the end of the speaker’s initial panic or mental chaos. However, the respite is short-lived, and the “Service, like a Drum” begins a fresh assault on both her physical senses and mind. The sound of the drum, like the tread of the mourners, is another attack on her sanity, an attack so fierce that she feels her mind “going numb.” Numbness is a physical sensation that stands as another example of the speaker’s struggle to convey her experience in understandable physical terms.

Lines 9–11
The speaker is now in what seems to be a state of shock, stunned and still like a corpse being readied for burial. However, in terms of the metaphorical funeral, her senses are still working, and again she uses the sense of hearing to describe the next stage of her breakdown. She hears the pallbearers “lift a Box,” the coffin in which, perhaps, her formerly sane self is contained. These men then “creak across” her soul, which calls to mind the previous sounds of “treading—treading” and “beating— beating”; like those sounds, this creaking is unpleasant because it is the result of men with heavy “boots of lead” trampling over her. What is being trampled upon is the speaker’s soul; the scope of the breakdown has expanded to include her entire conception of her own existence.

Lines 12–16
These lines describe the moment in the speaker’s collapse when she passes from the recognizable world of rationality to a state of mind conveyable only through similes and metaphors, even more strange than those previously offered. In the real, physical world, church bells are sometimes rung as a coffin is carried to a burial plot; these same bells are ringing here but are so loud that the speaker can only describe the sound as if all space is beginning to “toll.” Note how the sounds of the poem have grown increasingly louder and more menacing. The tolling is so loud, in fact, that “all the heavens” seem to be one great “bell,” and the speaker seems to be an “ear,” open to the barrage of noise that assaults it. As the speaker now has no hope of shutting out the dreadful tolling of the bells, the speaker’s soul has no hope of shutting out the madness that has possessed it. As funeral bells toll to mark the end of a human life, so the bells toll here for the figurative death of the speaker’s reason and sense of self.

The speaker then finds herself “wrecked” in some “solitary” place; this place may be physically the inside of her coffin (a most solitary place, indeed) or a figurative mental place, a description of which is too difficult for her to convey. All she can say is that she is “wrecked, solitary” there. The noise that has been growing throughout the poem is still present, so much so that silence seems a part of “some strange race” that she can no longer recognize. The ambiguity of the speaker’s physical and mental location in these lines suggests the difficulty of using concrete language to talk about abstract mental processes, a difficulty that will overcome her in the poem’s final line.

Lines 17–20
The poem’s final stanza concludes both the metaphorical funeral rites and the description of the speaker’s breakdown. The mourners have come, the service has been heard, and the pallbearers have carried the casket to the cemetery. The casket being lowered into the burial plot is used to metaphorically describe the final stages of the speaker’s ruin; however, while in earthy funerals a casket is rested on planks to support it prior to its being lowered into the earth, here the figurative “Plank in Reason”— the last flimsy bulwark against total insanity and devestation—snaps. As a casket is normally gently lowered into its dark earthen plot, here the speaker’s mind plummets into the darkness of madness, dropping “down and down” into more indescribable depths.

Each time the speaker thinks she has reached the limits of how much she can withstand, she finds that there is still another world awaiting her further down; with each plunge she is thrown deeper into madness until she has “finished knowing.” Now she can no longer trust her previously held assumptions about her own mind nor can she further describe her own mental processes in suitable terms. The poem’s final word, “then,” is ambiguous: either the entire poem is told from the point-of-view of one who has survived the mental “funeral” but who is now “finished knowing” anything for certain or the speaker’s ability to continue her story has (like everything else) been destroyed, and she has moved to a mental place that regular, ordered language cannot describe. Either way, the poem depicts the terrors of mental collapse in language that, by its ambiguous nature, reflects the difficulties in conveying the very events that cause and comprise it.