On the morning of the sixth of August, 1945, eight Jesuit priests were in their mission house near the centre of Hiroshima. At about a quarter past eight, a single bomb went off less than a mile away, and the city around them vanished in a flash of light.

Everything close to the blast should have been destroyed. Tens of thousands of people died in an instant. For miles, wood and stone buildings were flattened or set on fire. But the priests' mission house, about a kilometre from where the bomb went off, stayed standing. The eight men inside walked out alive, with cuts from flying glass and little else.

One of them, Father Wilhelm Kleinsorge, is not a legend. He is one of the six survivors the American journalist John Hersey followed in his famous account of that day, published in 1946. The priests pulled the wounded out of the rubble and carried them toward the river. Their broken house became a shelter.

There is a plain explanation for the building. Years before, a priest who was terrified of earthquakes had braced and double-braced its frame, and that bracing held when everything around it fell. The harder question is the men. One of them, Father Hubert Schiffer, was at breakfast when the light came. He said that in the years afterward he was examined again and again by scientists and doctors, more than two hundred times, who could not understand why he showed no lasting radiation sickness. He lived on for decades.

The priests had their own answer. In that house they prayed the rosary together every day, and they believed that was why they were spared.

Not everyone accepts it. Other people survived close to the blast too, in strong buildings and deep cellars. Father Kleinsorge himself was ill for years afterward. The Church has never called it a miracle.

But the house stood. The eight men walked out. And the ones who lived it never stopped saying why. Witnessed. New documented case every week. Subscribe.