“Prayer is religion’s hermit crab; it scuttles recognisably from age to age and purpose to purpose, while attempts to refute or confirm are left to grasp its shells. It endures, shaping the mind, altering the body, or reflecting and resisting the forces of modern life. In its irreducible variety and seeming gratuitousness, it remains a puzzle. But if prayer itself resists explanation, it can still be illuminating to map its dimensions.”