How is the banquet in scene 3 used as a symbol?

Prospero is using the Banquet for two reasons. One is a coming together as a final atonement for sins past. He uses Ariel to spell out exactly what Alonso and Antonio did wrong. I think the banquet scene is also symbolic of one of the major themes in the play, that is the disparity between appearance and reality. The banquet looks real to the mortals but disappears. In fact everything is unreal from the banquet to Ariel's shape shifting and deep voice. As all illusion vanishes, so does the sins of Antonio and Alonso. I think Prospero is wiping the slate clean.