Stanza 3 Summary

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

Of Visitors – the fairest –
For Occupation – This –

The speaker moves on from describing her poetry house but keeps the metaphor going by mentioning "Visitors," which we're going to go ahead and assume refers to the readers of the poetry.
Notice that she describes the readers as "the fairest," in the same way that she described her house as "fairer" in line 2.
So not only is the house the fairest of them all, but so are the readers who come to check it out.
Hey, isn't that us? Aw, shucks.
She must really mean it, too, because she separates "the fairest" with dashes.
We figure the "Occupation" that the speaker is talking about in line 9 is being a poet. Sure, it doesn't pay much—especially not in Dickinson's case—but it does occupy the time.
In case we were confused about this, the speaker separates the word "This" with dashes, emphasizing the fact that she's referring to the whole poem up until now as her job.
Living in an eternal poetry-house—sounds like a sweet job to us.
Almost to the end here, but we'd be selling you short if we didn't point out the assonance-consonance combo going on in these two lines.
Check out all the short "i's," "s's," and "t's" in "Visitors," "fairest," and "This."

The spreading wide my narrow Hands
To gather Paradise –

The speaker ends the poem with a similar image to that whole eternal roof/sky thing in lines 7-8.
Though she has "narrow Hands," she spreads them to try and grasp something huge and indefinable. So again we have a bit of a paradox.
Something small and contained is trying wrap around something that is ultimately uncontainable. How can we puny humans "gather Paradise"?
It seems like in the mind of the speaker Paradise is something eternal; it's the great unknown, the great beyond, Heaven, the Universe etc. It's impossible to hold that in your hands.
Of course, the speaker doesn't actually say that she succeeds in gathering Paradise. She just tells us that's what she's trying to do.
So even though writing poetry helps her expand her mind and her readers' minds, she still never quite reaches the thing for which she's reaching.
Hey, that's life right? And it seems like the speaker isn't too sad about it. It's the quest for knowledge and insight that keeps her going.