As imperceptibly as grief

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 who would be gone.

And thus, without a wing,
Or service of a keel,
Our summer made her light escape
Into the beautiful.