"When we have ceased to care"

When we have ceased to care
The Gift is given
For which we gave the Earth
And mortgaged Heaven
But so declined in worth
'Tis ignominy now
To look upon —

F (1737), Undated 

This poem seems to hearken back to an age-old anxiety for Dickinson: namely, the existence of heaven or some kind of afterlife. While she has several poems that anticipate a kind of dissatisfaction or apprehension about the restrictiveness of Heavenly life ("I shall know why -- when Time is over", "I never felt at Home -- Below"), this poem is interesting in that it appears to feature a deceased speaker who is now aware that there is nothing after death and is unsuccessfully trying to cope with that emptiness and the ultimate realization that, without a heaven or hell, the time they spent worrying about sin is essentially meaningless. 

If "The Gift" that is being given in this poem is taken to mean the answer to the burning question: "What is the meaning of life/suffering?" it can be said to bear a considerable amount of tonal and lexical similarities to "I shall know why -- when Time is over." While the speaker of that poem finds themselves in Heaven being granted detailed explanations of "each separate anguish" by Christ himself, they recognize that these answers are coming to them after they have "ceased to wonder why" as they are not in a position to fully utilize them. The speaker of this poem, on the other hand, has outright "ceased to care," a decidedly more visceral reaction to the nothingness that now surrounds them. 

To sin is "mortgage Heaven" and risk one's place in it.

The use of the verb "gave" in line three is perhaps the most difficult aspect of the poem to comprehend. The Dickinson lexicon offers a host of possible options for a meaning, but the most appropriate in this context may be its definition of it as to "Commit: yield to the power of." In a sense, we commit our lives to Earth in the hopes that, at the end of them, we will be given "The Gift" that allows us to prescribe them a true reason and purpose. The phrasing of "mortgag[ing] Heaven" and "ignominy" can both be boiled down to the act of sinning, which Christian doctrine would obviously expect one to abstain from. The speaker, knowing now that, in actuality, there was no place in Heaven to jeopardize, recognizes how "declined in worth" the concept of their sins looks to them. 

While the speaker's somewhat paradoxical position of narrating from a non-existent afterlife may simply be chalked up to the artifice of the poem, it does offer another intriguing possibility, one that suggests they may be stuck in some kind of limbo. Knowing Dickinson's up and down relationship with faith and belief and her resistance to fully converting to the religion of her time, the speaker here may be channeling some kind of purgatorial apathy, a place in between Heaven and Hell where the sins they committed bear less weight due to there being no chance of redemption. The ending dash in the final line "To look upon --" may also imply that they're going to have to continue looking upon those sins in perpetuity.

http://edl.byu.edu/lexicon/term/614673