When witnesses disagreed there was a procedure for settling the matter: one of them had to undergo an ordeal, either pick up a red-hot iron bar and carry it ten paces, or plunge his hands into boiling water and pull out a stone. In theory, God would protect a man who was telling the truth. In practice, Aldred had never known anyone to volunteer for the ordeal.

Often it was clear which side was telling the truth, and the court would believe the more credible witness. But Wynstan’s case would have to be heard in the shire court, which would be presided over by his brother. Ealdorman Wilwulf would be shamelessly biased in Wynstan’s favor. Aldred’s only chance would be to produce evidence so overwhelmingly clear, backed up by oaths from men of such high status, that even Wynstan’s brother could not pretend to believe in his innocence.

He wondered what drove a man like Wynstan to become a forger. The bishop had a life of ease and pleasure: what more did he need? Why risk losing everything? Aldred supposed that Wynstan’s greed was insatiable. No matter how much money and power he had, he would always crave more. Sin was like that.

He arrived at Shiring Abbey late in the evening on the next day. The monastery was quiet and he could hear, from the church, the psalm singing of Compline, the service that signaled the end of the day. He stabled his horse and went straight to the dormitory.

In his saddlebag he had a gift from Combe Abbey, a copy of Saint John’s Gospel, with its profound opening words: “In principio erat Verbum, et Verbum erat apud Deum, et Deus erat Verbum.” In the beginning was the Word, and the Word was with God, and the Word was God. Aldred felt he could spend his life trying to comprehend that mystery.

He would present the new book to Abbot Osmund at the first opportunity, he decided. He was unpacking his bag when Brother Godleof came out of Osmund’s room, which was at the end of the dorm.

Godleof was Aldred’s age, with dark skin and a wiry frame. His mother had been a milkmaid who was ravished by a passing nobleman. Godleof did not know the man’s name and hinted that his mother had never known it either. Like most of the younger monks, Godleof shared Aldred’s views and got impatient with the caution and parsimony of Osmund and Hildred.

Aldred was struck by Godleof’s worried look. “What’s happened?” he said. He realized that Godleof had something on his mind that he was reluctant to say. “Out with it.”

“I’ve been looking after Osmund.” Godleof had been a cowherd before he came to the monastery, and he used few words.

“Why?”

“He’s taken to his bed.”

Aldred said: “I’m sorry to hear that, but it’s not really a shock. He’s been ill for a while, and lately he’s had trouble walking down the stairs, never mind up.” He paused, studying Godleof. “There’s something else, isn’t there?”