“Listening to Noam Chomsky,” said a psychologist in her 50s, “always turns me on.”

This psychologist is by no means alone. A few months ago, in the Harvard Coop, a 20-something customer explained to her friends as they all walked past the cash registers, "I have such a crush on Noam Chomsky!"

A plethora of new findings, however, suggest that the experience of desire may be less a forerunner to sex than an afterthought, the cognitive overlay that the brain gives to the sensation of already having been aroused by some sort of physical or subliminal stimulus ...