She lay as if at play

She lay as if at play
Her life had leaped away—
Intending to return—
But not so soon—

Her merry Arms, half dropt—
As if for lull of sport—
An instant had forgot—
The Trick to start—

Her dancing Eyes—ajar—
As if their Owner were
Still sparkling through
For fun—at you—

Her Morning at the door—
Devising, I am sure—
To force her sleep—
So light—so deep—
                                                       F412 (1862)  J369

Dickinson takes a break here from the weighty topics of previous poems to return to the theme of what death looks like on the face of the recently deceased. The subject here is a young girl (I think three or four earlier poems had a dead girl child in them, too). Ladies of Dickinson's day often wrote these sad child-death poems, and they were avidly consumed by readers. This one is a bit heart wrenching because Dickinson sketches a lively child with "sparkling" and "dancing" eyes who seems to have died without much warning. Her life "had leaped away" as if just jumping up to get something. 

Dead children were often posed and photographed as if

     they were only sleeping

          Less clear to me is what the poet means by "Her Morning at the door." I think Dickinson intends the homophone of Morning and Mourning; I think she also means the re-birth connotations of morning. But this particular earthly morning, the child was not awakened by the sun or by her mother. This particular morning took great pains to make sure the child would never wake again in her little bed. There's an ominous quality to a morning that was "Devising" the sleep of death and how to "force" the child into it. The reader pauses a bit at the line, but "Morning" seems so innocuous that how many of us really think it had such deadly intent? I think Dickinson was intending this irony.
          Except for the last line of each quatrain, Dickinson uses iambic trimeter throughout. Each quatrain is divided into two rhyming lines. The simple scheme lends a childish quality to the poem. The last lines of the stanzas are in dimeter; each word is only one syllable. These lines are neatly divided by both meter and sense: one reads them as pairs: "But not : so soon"; "The Trick : to start"; "For fun — : at you"; "So light — : so deep." The effect is disruptive — just as the child's sudden death was disruptive. The last pair with its "light" and "deep" is a thoughtful pairing that asks the reader to think about a child's death sleep — at least this child's. Her "sleep" looked so light, but went so deep. One also hopes that the experience from the child's perspective was the same: so light — so deep.