Now that I'm not falling asleep typing and, hopefully, the words are not missing letters, I'm continuing the last entry...
I feel like some of Dickinson's point in writing this poem is to point out that everyone has a beginning, or a morning. We are given hundreds of starts, literally as each day begins and figuratively with each opportunity that comes our way. The night, or completion, only comes to some. There are those who do not see the end of the day-- those who die unexpectedly or who do not see the end of the opportunities they were given. Some see the "night" or conclusion to hopes and dreams. But some do not.
At the end of this poem lies the rare Auroral Light. It is something that a very small percentage of the world gets to see, and I would think that it would be a thing of wonder and even rarer a sight in Dickinson's time. Today there is a large percentage of the world that will never see the aurora, and I believe that Dickinson uses this as a metaphor for those who never see the miraculous or the rare. So many people live ordinary lives, perhaps even content but never aware of what the amazing and unique experiences that lie just beyond them. Some are aware of such things, but some people have no interest in pursuing them. Likewise, others are aware of things like the auroral light but have so convinced themselves that it is an experience they will never have or deserve.
Morning, night, and the auroral light are possiblities of everyone. There is potential to reach each thing. And how few people actually pursue beyond the morning? I think there is a lesson in greatness found in this poem. Dickinson leaves this poem with an open thought for the reader. Namely, which do we pursue or find: morning, night or auroral light? Are we content with what we experience? And what more could there be, waiting for us to recognize as an opportunity and waiting to be experienced as miraculous?