'Passed sway with sunny May'

I cannot tell you how it was;
But this I know: it came to pass--
Upon a bright and breezy day
When May was young, ah pleasant May!
As yet the poppies were not born
Between the blades of tender corn;
The last eggs had not hatched as yet,
Nor any bird forgone its mate.

I cannot tell you what it was;
But this I know: it did but pass.
It passed away with sunny May,
With all sweet things it passed away,
And left me old, and cold, and grey.

-- Christina Rossetti, "May''