Joan of Arc heard voices.Stravinsky and Mozart heard whole symphonies.Einstein solved problems without thinking.Archimedes solved his in the bath.Churchill felt protected by a guiding hand.What about you?Have you had an unknown Guest?Throughout the ages people have sensed the existence of a benevolent force intervening from time to time in their lives as if to offer them help and protection - or to chasten them. The good fairy of folklore and the guardian angel of Christian tradition belong in this category. Socrates said that he had heeded the voice of his 'daemon' all his life, and it had never let him down. Churchill sometimes had 'a strong feeling'; he told an audience of miners during the Second World War, 'that some guiding hand has interfered'.In The Unknown Guest Brian Inglis explores the historical and present-day evidence of the force. In perhaps its most familiar guise it operates as the 'muse' for writers and artists. And many of us have felt that chance and luck can't explain away hunches, premonitions, meaningful coincidences and extra-sensory perceptions. Brian Inglis concludes that we don't know enough to be sure about the source of these promptings but the evidence is impressive enough to be worth examining afresh.