What lips my lips have kissed, and where, and why -
Edna St. Vincent Millay (1892-1950)
What lips my lips have kissed, and where, and why, I have forgotten, and what arms have lain Under my head till morning; but the rain Is full of ghosts tonight, that tap and sigh Upon the glass and listen for reply, And in my heart there stirs a quiet pain For unremembered lads that not again Will turn to me at midnight with a cry. Thus in winter stands the lonely tree, Nor knows what birds have vanished one by one, Yet knows its boughs more silent than before: I cannot say what loves have come and gone, I only know that summer sang in me A little while, that in me sings no more.
(found in David Lehman (ed.), The Oxford Book of American Poetry)