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 Gandhi 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.