Life is death we're lengthy at

Life is death we're lengthy at,
Death the hinge to life.
                            F502 (1863)

Dickinson included this aphorism in a letter to her cousins (L281) in May 1863. Franklin, and no doubt others, have classified it as a poem. It's a juicy couple of lines and bears scrutiny. In the letter's preceding passage, Dickinson informs her beloved young cousins, Fanny and Louisa, that Mrs. Edward Hitchcock, has died.

Jennie Hitchcock's mother was buried yesterday, so there is one orphan more, and her father is very sick besides. My father and mother went to the service, and mother said while the minister prayed, a hen with her chickens came up, and tried to fly into the window. I suppose the dead lady used to feed them, and they wanted to bid her good-by.
    Life is death we're lengthy at, death the hinge to life.
Love from all, Emily

The purpose of the remarks is clearly consolatory. The message is conventional enough: The dead woman is now in a better place. Dickinson's aphorism conveys this by blurring the boundaries between life and death. Life is a process of dying – one that begins at birth. A more true life, she suggests, begins once death is complete. It is then that the door to eternal life opens. It would not open if not for the "hinge" of death.
        

Dickinson had written many poems by this time that include references to eternity. Some of them describe or allude to a Christian heaven complete with saints and angels. Others, though, are less sanguine. The dead seem to wait forever in their tombs, as in F124, "Safe in their alabaster chambers," where "Firmaments – row –" and "Worlds scoop their Arcs" while "the meek members of the Resurrection" sleep away in their tombs.
         But that is not the comforting note she strikes with her younger cousins. She wrote them a year earlier after their father's death and included a longer poem with another reference to death as a door to life.

It is not dying hurts us so, –
'Tis living hurts us more;
But dying is a different way,
A kind, behind the door, –
….
        F528, J335

The idea of death opening the door to heaven is common enough. But Dickinson expresses it powerfully in her concise aphorism. She does not say "heaven," it should be noted; only "life." Such life is to be joyfully anticipated, she implies, but she stops short of calling forth the image of Christian heaven.