When she says: "I felt a funeral in my brain, and mourners to and fro, kept treading, treading till it seemed that sense was breaking through... " She focuses on the sensation of being in the body, feeling the body's substantiality and solidity, and the heaviness caused by gravity pulling on its very substance.
When she says ..."And then I heard them lift a box and creak across my soul, With those same boots of lead, again the space began to toll..." I believe this to be an expression of the awareness a "Light Body" expieriences, seeing , tasting, touching, and the like. The body that is within the heavy or outer body.
"As all the heavens were a bell, and being but an ear, and I, and silence, some strange race, wrecked, solitary here" I believe is a reference to the phase where the "Light Body" becomes separated from the "Heavy Body" and everything floats free. "And then a plank in reason broke, and I dropped down, and down, and hit a world at every plunge, and finished knowing then-" I believe this to be gently and gradually dying and into the light and free of knowing. Thinking that all that comes to mind is old and are just old thoughts, and we do not have to hold to them. Giving a new birth to ourselves, to observe peace, mercy, kindness, and healing the pain we suffer from.
The poem is only superficially about the funeral; It is "concerned with the intuitive knowledge of eternity gained through an intimation of death....."
In a sense