I wonder if one can ever truly know the separation between exterior expression; appearance through costume, clothing, ritual garb, skin, hair, sounds, words, movements; and the inner individual person?
For example, the more time we spend in a business suit, the more we feel we are a part of business, and the more we are perceived by others as such. We tend to think the less time we spend looking a certain way, the less we are like the associations of that image. A costume is usually not something that is regularly worn by the wearer.
Yet I think there are exceptions. Sometimes we can find a costume that fits ourselves better than our daily uniforms, even a better side of ourselves. However just as we are amalgams of perspective, so too are costumes. There can always be more than one interpretation of the wearer and their costume, if it is even called a costume.