John Denver, a “soul-brother” of mine, wrote:
“There’s a longing deep within the wandering soul. It’s like the half that understands it once was whole; like the two who only dream of being one; like the moon whose only light is in the sun.”
(“Wandering Soul”, unreleased song by John Denver)

Michael Jackson understood too, profoundly and tragically :
“It’s hard to tell them what I feel for you. They haven’t ever met you, and no one has your picture. So how can they ever understand your mystery? Let’s give them a clue: Two birds sit in a tree. One eats cherries, while the other looks on. Two birds fly through the air. One’s song drops like crystal from the sky while the other keeps silent. Two birds wheel in the sun. One catches the light on its silver feathers, while the other spreads wings of invisibility.
It’s easy to guess which bird I am, but they’ll ever find you. Unless…
Unless they already know a love that never interferes, that watches from beyond, that breathes free in the invisible air. Sweet bird, my soul, your silence is so precious. How long will it be before the world hears your song in mine? — Oh, that is a day I hunger for!”
–MJJ (“Two Birds” from his book “Dancing the Dream”, published 1992)