Could someone analyse the structure of this poem?

As imperceptibly as Grief
The Summer lapsed away—
Too imperceptible at last
To seem like Perfidy—
A Quietness distilled
As Twilight long begun,
Or Nature spending with herself
Sequestered Afternoon—
The Dusk drew earlier in—
The Morning foreign shone—
A courteous, yet harrowing Grace,
As Guest, that would be gone—
And thus, without a Wing
Or service of a Keel
Our Summer made her light escape
Into the Beautiful.

(It was written by Emily Dickinson who was very solitary and rarely left the house.) also, it would be appreciated if someone took a quote and picked it apart e.g. connotations of words etc. thanks.