by Christina Rossetti
I cannot tell you how it was,
But this I know: it came to pass
Upon a bright and sunny day
When May was young; ah, pleasant May!
As yet the poppies were not born
Between the blades of tender corn;
The last egg had not hatched as yet,
Nor any bird foregone its mate.
I cannot tell you what it was,
But this I know: it did but pass.
It passed away with sunny May,
Like all sweet things it passed away,
And left me old, and cold, and gray.
You can find this in The Complete Poems.