And lets the brain away
The fellow will go where he belonged —
Without a hint from me,
And the world — if the world be looking on —
Will see how far from home
It is possible for sense to live
The soul there — all the time.
F585 (1863) J1727
This poem reminds me of Dickinson's reply to Thomas Higginson when he asked her to define poetry: "If I feel physically as if the top of my head were taken off," she wrote, "I know that is poetry." She expands on that notion here in this lightly whimsical poem. The brain here is portrayed as her consciousness and thinking self locked tight inside her head. Just as a prisoner might flee for home if the jail doors opened, so might the brain rush away if the lid of the poet's head ever "gets off" her head.
There are several aspects of the self that make an appearance in this poem making it a bit ambiguous. There is the "me" whose head it is, the brain who is confined under the lid of that head, the "sense" – which is probably synonymous with the brain, and the soul. That soul seems to exist on a different plane than that in which Emily Dickinson baked bread and tended her father's house. It belongs to some higher realm than that of daily chores. If it could, her sense/brain would fly away to join the Soul leaving the daily Dickinson at home to cope as best she could.
The saying "head in the clouds" gets at something of the same idea, but I think Dickinson is getting at the nature of being a poet. We've seen her soul explore the expanses of the cosmos looking for God or struggling for freedom from the existential threats of a death-haunted world. We've seen her mind searching and processing both inner and outer depths, reporting her findings in poetry in language and imagery so powerful and fresh that her readers' heads are in danger of being taken off.
The last stanza is a prescient depiction of how the world has come to see Emily Dickinson and her remarkable poetry, for the world has indeed been "looking on". Individually and collectively, readers marvel at just how far from her cultural and familial environment Dickinson's sense and soul resided.