the conceptual theme of Mirage was reportedly a music box... the music had that sort of tinkly, plinky sound and airy feel of music played on a music box which is a brilliant concept. Not every song quite fits, but the ones that do are among the best: Gypsy, Hold Me, Can't Go Back, Wish You Were Here other Stevie songs were deemed too dark for this collection (Smile at You for example). I know there's some debate over when Make Me a Mask came into being, but to me it sounds like it fit this concept really really well.
