Stanza IV Summary

Get out the microscope, because we’re going through this poem line-by-line.

With Blue – uncertain – stumbling Buzz –

This fly isn’t some kind of graceful, beautiful insect like a butterfly.
Again, the speaker emphasizes the sound of the fly, what she calls the "Blue – uncertain – stumbling Buzz – ."
This is a really great Dickinson line. Do you feel how the poem itself stumbles uncertainly right here? Think of a how a fly buzzes around, then lands, and then buzzes around again. Those dashes break up the line with pauses just like a fly breaks up its flight. The sound of the word "buzz" mimics the sound of the fly.
We are pulled into the moment by this line. The speaker forces us to focus all our attention on this little fly.

Between the light – and me –

Here we learn that when the fly "interposed," it was coming between the speaker and "the light."
We think there are two ways to read this. On the one hand, it might just be that the fly has come between the dying woman’s eye and some light in the room, like a candle or a lantern.
On the other hand, she’s been talking about some pretty spiritual stuff, like that King who’s supposed to show up. So we suspect that the light is also a metaphor for what comes after death, the thing that we approach and enter when we die. It’s hard for us not to imagine some little kid shouting, "Walk toward the light, Emily!"
Then again, Dickinson never got to see a cheesy TV movie about near-death experiences.
In any case, this fly has messed things up. We were all moving quietly toward the light, and this poem was moving toward a normal ending. Then this stupid fly showed up, and pretty much wrecked the whole thing.
Or, made it that much better, if you happen to like Dickinson’s slightly twisted perspective.

And then the Windows failed – and then
I could not see to see –

And then, just like that, it’s over.
The speaker tells us that "the Windows failed." As far as we can tell, that means that her eyes closed, that she lost contact with the outside world. You know how people sometimes call the eyes "the windows of the soul?" That’s what we’re dealing with here.
Of course Dickinson has to put her own twist on this moment. The speaker tells us that she "could not see to see." This doubles the feeling of isolation, of change, of the failure of the senses. It’s a haunting way of talking about the moment of death.
Even so, it’s a little hard for us to say exactly what she is describing here. How do you "see to see?"
We think this last image is meant to be hard (or even impossible) to pin down. The speaker has crossed over to the other side, and the experience can’t quite be put into words.
That’s what’s spooky and a little disturbing about the end of this poem. First there is family, and quiet, and keepsakes. Then there’s a fly, and then there’s a mysterious nothingness. It’s not a very comforting image of the final moments of life.
Dickinson doesn’t go out of her way to make you feel better, either. She just lets you sit with those two final images: a weird little fly and a dark emptiness.
Creepy, huh?