Hindu and Greek mythologies teem with stories of women and men who are doubled, who double themselves, who are seduced by gods doubling as mortals, whose bodies are split or divided. In Splitting the Difference, the renowned scholar of mythology Wendy Doniger recounts and compares a vast range of these tales from ancient Greece and India, with occasional recourse to more recent "double features" from Dr. Jekyll and Mr. Hyde to Face/Off....