The shadow is passing things as if it were a person passing a paper, basically.
Explanation:
As shadows do, they move with the light. This is being taken literally as if the shadow is moving of its own accordance. And while it moves of its own accordance, it decides to take its owner's smiles and tears with it so the owner feels nothing. The personification basically helps you to see the way the shadow catches the gently falling tears and snatches the smile from your face. It can help you to hear the sudden choked on sob, hear someone stifle a laugh. I don't think smell and taste can be applied here, but it can cause you to feel the cold, empty, devoid-of-all-emotion area that the person and shadow seem to be in. Sorry this was long, but I hope it helps!
