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.