'Lord Jesus Christ, Son of God, have mercy on me.' This ancient prayer has been known and loved by generations of Christians for hundreds of years. It is a way of entering into the river of prayer which flows from the heart of God: the prayer of God himself, as Jesus continually prays for his people and for the world he loves. Simon Barrington-Ward teaches us how to use the Jesus Prayer as a devotional practice, and opens up the Bible passages that are crucial to understanding it.