What Do Dreams Do?

We have puzzled over dreams for centuries. From ancient societies, believing dreams to be messages from the gods, Freud's theory of dreams revealing our unconscious minds to modern day experiments in psychology and neuroscience, dreams continue to fascinate but also be a source of mystery. Are dreams just mental froth or do they have a purpose?

This book argues that, originally, we dreamed to survive. Dreaming brains identify non-obvious associations, taking people, places, and events out o...