Melvyn Bragg examines the purpose and effects of prayer. Why do people pray? What did prayer ever do, the cry goes up, for those millions upon millions of non-combatants, civilians, children, innocents, whose lives have been ended by a savage variety of brutality? Do we pray for the benefit of God or for our own sake? Is it a good Christian weapon as Martin Luther defined it and as Mahatma Ghandi put it the most potent instrument of action; or is prayer simply the most essential form of self analysis? Or was Ovid right to see prayer as a way of changing the mind of God, when he wrote in The Art of Love, Even the Gods are moved by the voice of entreaty. People have prayed since the dawn of language - but why, and has it done us any good?With Professor Russell Stannard, physicist, religious writer and author of The God Experiment; Andrew Samuels, Jungian analyst and Professor of Analytical Psychology, University of Essex.