Dickinson describes the fly's path as uncertain and a stumbling Buzz - which is a metaphor for how ready she was to die, but then this unexpected fly came out of the blue to distract her from what is going on at the moment. However, even through the distraction and the unexpected, she sees the "light", as if the fly is transitioning her to the afterlife. "And then the Windows failed -and then I could not see to see -" represents death, and she's finally able to close her eyes and at last pass away.