Be sure to notice the past tense here. The speaker is already dead, so she must be speaking to us from beyond the grave. Even if this doesn’t give you any really clear ideas of what or who this person is, it definitely puts us in the spiritual realm. This raises all kinds of questions about life after death, heaven, hell, ghosts, etc. And all in one short and simple first line!
For the last Onset – when the King Be witnessed – in the Room – (lines 7-8)
This is as close as Dickinson comes to giving us a definite idea of what happens when we die. And even then, it’s not really all that clear. Apparently at the moment when you die, someone or something called "the King" appears, or is "witnessed" in the room. Even that is a pretty boiled down version of this image, with some guesswork to fill in the blanks. What is clear is that this is a spiritual metaphor. Dickinson is trying to convey something about the world beyond our everyday reality. There isn’t much chance that an actual king is going to stroll in here. This "King" represents a powerful, unusual force. Maybe it’s God or maybe it’s some other mysterious creature or idea. Dickinson is certainly focused more on the strange power of spiritual ideas than on imagining the details of what happens when you die.
Between the light – and me – (line 14)
Now this might just suggest that the famous fly came between the speaker’s eyes and the light. But check out how much spiritual language there is around this moment. We are halfway between the real, physical world and something else. So we think it’s likely that Dickinson wants this image to suggest something more. This fly is interrupting the speaker’s line of sight. But it may also be interrupting her connection with the next world, with whatever lies beyond death.
In one sense, this fly pushes all the spiritual musings to one side because, after all, he’s just a fly. In another sense, though, he makes all the spiritual possibilities deeper. Maybe he represents something ugly and scary and evil about the world that prevents people like our speaker from reaching the light after death. We’re kind of out on a limb here, but we think Dickinson put us there, with all these big symbols like the King and the light and the fly.