despite the bold FACT in asmonet’s answer, I think that you will find that most people require stimulation in order to orgasm. I’m sure this varies on a person my person basis. I don’t think in most situations mental stimulation would be enough. it would however likely kick start the process.
Ladies, we’ve all had THOSE dreams and we can usually go right back into them without moving an external muscle. Guys, it would kill you to know what we can do.
Spontaneous orgasms can happen to both men and women. A man’s wet dream, for instance. It could also be that the woman is aroused by reading the novel, and a shift in the sitting position causes friction in the clitoral area, thus facilitating an orgasm.