You Can Be Me When I'm Gone
The Principle of Change is inescapable. Older than the universe itself, it flows through Time and Space and souls, and nothing can withstand it. This is the reason why the paths in Destiny's garden are twisting and winding; and the Time Lords, with their four-dimensional vision, are aware of the thousand possible forms it can take. When the moment comes and a change occurs, the consequences can be far-reaching. But when the summer leaves fade and everything darkens, don't the leaves remain in the world, feeding the earth in their new form? Death, they say, is the biggest change. But even then ghosts remain.
"All around me darkness gathers,
Fading is the sun that shone;
We must speak of other matters:
You can be me when I'm gone."
Morpheus, the blood of his son on his hands and heavy iron chains on his stubborn heart, stands up against the Furies and tries to defend his kingdom. He sends his raven, Matthew, away. Horrified, Matthew objects, wanting to stay beside him till the bitter end and fight. With unexpected gentleness Morpheus persuades him to bring him his Sister. Matthew leaves. Dream sacrifices himself and the Dreaming is saved.
Matthew had withdrawn to the cave and wouldn't come out, not even to Morpheus' burial. The agony of his master's death lies on his heart like a stone, and so he will not talk to anyone. When Eve tries to comfort him in her tender, motherly way, he buries his head under his wing and mutters to her to go away.
"Flowers gathered in the morning,
Afternoon they blossom on,
Still are withered by the evening:
You can be me when I'm gone."
The Doctor is horrified when he learns that the Daleks had survived. And not merely survived: tens of thousands of ships are now orbiting Earth, ships whose sole mission is to exterminate any living soul. He had burned down his world for nothing. His people had died for nothing. He tricks Rose Tyler and sends her back home, screaming and banging on the TARDIS doors. He doesn't tell her how he feels about her. The Doctor sacrifices himself and Earth is saved.
Rose Tyler stares, terrified, at the Doctor. He laughs amid his pain, tells her he wanted to do so much, so much with her. Now it will never happen. She begs him to do something, to save himself, not to die. He suddenly bursts into intense beams of light, burns, dissipates, and is gone. A different man lies on the floor instead of him.
"The King is dead. Long live the King!"
There's no way Matthew will recognize Daniel. He's a cute kid, but certainly not his boss. He is Dream's raven, not this white-haired, white-cloaked imposter's, never mind how much his eyes are like Morpheus'. Daniel tries to reason with him, telling him that every jewel has many facets, and sometimes it's so easy to mistake the shining of one facet with the entire jewel. He is Dream of the Endless, just like Morpheus and just like the Dreaming itself. Matthew doesn't, will not understand.
Rose looks at the stranger lying unconscious on her bed and tries to convince herself that this is the Doctor. After all, she had seen him change. But he is very different now, and when he regains consciousness she understands just how much: it's not only his face that's different, his personality changed, too. This isn't her Doctor, even though the gleam in this one's eyes when he looks at her is so much like his. Rose Tyler fights back her tears.
Only the realization that Daniel is still an infant, and the ensuing pity, softens Matthew's heart. He's willing to help him a little, teach him a little, even though he still wouldn't be his raven and prefers to die. The pain settles deep in his heart, but as the days go on it gets dimmer. Soon Matthew will not know why he's crying. Eventually Morpheus will be forgotten.
A long time passes until Rose feels again love for the Doctor. It's a different emotion, now, but he is a different man. And when she is torn irreversibly from him on the bleak, frozen beach in Norway, she feels again the pain of the first tearing. The parts of the puzzle finally come together. The change is internalized.
"Only the Phoenix arises
and does not descend.
And everything changes,
And nothing is truly lost."