I was re-reading a novel called Executive Orders by Tom Clancy yesterday, and saw that the author had placed a poem in the foreword that I thought appropriate for the situation in which the Order of the Phoenix ended.
This poem is called "Ascension" and was written by Colleen Corah Hitchcock. As it is copyrighted, I would like to extend all credit to Ms. Hitchcock, and hope she doesn't sue me. This poem is as follows:

And if I go,
While you're still here...
Know that I live on,
Vibrating to a different measure
-Behind a thin veil you cannot see through.
You will not see me,
So you must have faith.
I wait for the time when we can soar together again,
-Both aware of eachother.
Until then, live your life to its fullest.
And when you need me,
Just whisper my name in your heart,
...And I will be there.