Stanzas 3-4 Summary

Stanza 3

Somebody flings a Mattress out —
The Children hurry by —
They wonder if it died — on that —
I used to — when a Boy —

• Okay, this speaker is definitely verging on Peeping Tom territory. He's just staring at this house, noticing everything. 
• In this stanza, even the kids are getting involved. But first, an unnamed, faceless "Somebody" flings out the mattress. You can picture just the hands visible before the big floppy thing flies out to land on the ground. 
• There's something weirdly disturbing about this, isn't there? We're not used to having our beds brought outside much less tossed (unless there's some kind of yard sale). But back in the day, people would regularly air out their mattresses come springtime. And of course you'd want to air the thing out if there are any death cooties on it. And that's what you think right away, that whatever caused this death is still lingering there.
• Even the children can smell it. They're hurrying by because it freaks them out, wondering if "It" died. And here the line breaks, to give particular emphasis to "on that," the flung mattress. 
• "It"? Does this poem refer to the dearly departed as "It"? It sure does. This dead person has no identity. It doesn't even have a gender. Why? It's as if the death has dehumanized this person, has made it—like the flung mattress—just a thing. 
• The speaker makes comes back in line 12, and—tada!—though the poet is female, the speaker is most decidedly not. He announces that he, too, used to wonder about death when he was a boy himself. He's been watching and noting the signs of death for all these years, because now, it's implied, he's a grown man.

Stanza 4

The Minister — goes stiffly in —
As if the House were His —
And He owned all the Mourners — now —
And little Boys — besides —

• Out with the mattress, in with the minister. The breath of the corpse might be arrested, but the house continues with the in and out of people and things. 
• Look at how Dickinson describes the minister. Yes, he gets a capital letter (as most of her nouns do), but he is said to enter "stiffly." Not only does that call to mind someone fake and formal, but it's hard not to associate "stiff" with the stiff lying inside still. The slang word for corpse, stiff, no doubt was inspired by the rigor mortis that sets in. It came into usage right around when Dickinson wrote this poem, so she could be playing on that meaning of the word. 
• This minister comes in all high and mighty, it would seem, acting like the House is his, when it really isn't, and that he owns it all, right down to the people mourning. Some nerve. It's not explicit, but there's definitely the feeling that he's getting too big for his britches.
• There's the word "now" set off on its own between dashes (the way "alway" was above in Line 4). This punctuation gives the word its, well, moment. This is the minister's moment of drama. He gets to stride in all formal and stiff and lord his power and authority over everybody, even the boys, who might stand in awe of the minister's position and duties.