The Infinite a sudden Guest — Death

The Infinite a sudden Guest 1
Has been assumed to be-
But how can that stupendous come
Which never went away?
(F.1344/J.1309)
[1] The Infinite:: the death. sudden Guest:: this poem was written in 1874, the year Emily's father Edward Dickinson (1803–1874) died in Boston while giving a speech.
[2] assumed:: arrogated; everyone assumed death will come one day, but still a sudden to most of us.
[3] stupendous:: astounding, the astonishment of one's death.
[4] never, away:: the feeling never went away.