In real life people take off their clothing for various reasons. In a novel, unless it drives the plot, theme, or story line there is little reason to document the action, consequences, or reasons for your character's nudity.
In my novels, especially the Aegypt novels www.AegyptNovel.com, I use nudity with a specific purpose in mind. I'm giving away real secrets here, about my writing and my ideas on writing.
Back to Eden
One of the main themes in the Aegypt Novels is 'back to Eden' driven by Leora. Leora, the Goddess of Light, is not perfect, but she is the archetype Eve--the perfect woman. Her nudity demonstrates and represents her closeness to God. Likewise Lumie're, her daughter, and the Goddess of Darkness, in her time, is clothed and uncomfortable unclothed. These themes play throughout the novels with this specific purpose.
Good/Purity and Evil/Impurity
Leora, the Goddess of Light, is naked at certain times, and Leila, the Goddess of Darkness, is always naked. The contrast within the books is their stature and pose--the purpose for their nudity is to represent the concept the Jews call Eve/Lilith. Eve was created perfect, the mother of mankind, Lilith was created perfect and the mother of demons. The concept displays how beauty and perfection of form does not equate to beauty and perfection of purpose.
I do cultures and societies in my novels. Many cultures are driven by clothing, many are not. The contrast and comparison is wonderful. The play between them significant. A powerful contrast in many cultures is their view of nudity. The ancient Irish culture abhorred it, while the Greeks thought it was completely normal. This comparison/contrast based on clothing, or the lack of it, provides a powerful driver for plot lines. I do this a lot in my newest novel Dana-ana.
Shock refers to the characters and the readers. The shock value of the use of nudity in a fashion the reader may not expect can be powerful--the shock value between characters whose cultural perceptions are very different is priceless. These cannot drive a theme, but they provide some power within a theme--especially a theme about culture.
All these ideas work together on the page. They are self supporting and although can be used separately, gain power through being used together.
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