Dreams form the flipside of human consciousness: they are perennially fascinating and unpredictable. They have shaped history, art, culture, science, and religion in countless ways. Christianity accepts them as sometimes divinely inspired, but early psychology saw them as 'the royal road to the unconscious', or as a primordial soup of symbolism. So what are dreams? Why do we have them? Do Christians dream of Biblical sheep? And what attention – if any – should we pay to them?