On Saturday night a patch of land outside Kraków became a field of light. From a distance, the field had a mellow glow. Up close, you could pick out individual faces, lit up from below by candles. In the Campus Misericordiae (“Field of Mercy”) stood 1.5 million young people: the hope of the Church in a turbulent and often dispiriting 21st century.

As you looked at that shining field, it was hard not to think back to events earlier that week in a village church in Normandy. Fr Jacques Hamel, an octogenarian priest, was slain at the altar by Islamists. He is said to have fallen backwards after his attackers slit his throat, so it is possible that the last thing he saw were the candles burning on the altar where he had just been celebrating Mass.