My son moved out, the real one, the official one, the not living at home for sure anymore one. But his spirit, that is to say his STUFF lives on. He took what he "needed," although I personally think he needs more than he believes he does. He doesn't want to be anchored to things; I get that. However, he doesn't seem to mind anchoring us to his things, namely the items that he left here.
When your children move out for the first time, they take their things, and leave the memories. That's one of a parent's functions, I suppose, to be the repository of memory. But so much memory is locked up in stuff. Is the hideous peanut-shaped jar junk, or is it a precious childhood artifact? If I get rid of the admittedly brilliant 6th grade spanish class poster, will someone regret it? There are reams and reams of drawings; I have no idea what to do with them.
It's not so easy moving a child on. Memories seem ephemeral, but they attach themselves. They are sticky, and their things have weight.