He was naked. Mud caked his chest, his arms and his face like a potter’s effigy, cracked in the sun; below the waist his skin was washed clean and white by the river. He hauled the bucket up to the slanting table and tipped it out. Mud slithered down the ladder, slopping over the rungs and leaving a residue of white clay clinging to the boards. The man scooped it off and deposited it in the trough, which he then filled with water from his bucket and stirred with his hand. White clouds billowed and swirled in the water, but where sunlight touched the bottom, through the whorls and eddies, he caught the unmistakable sparkle of gold.

Something at the mouth of the river caught his eye. At first he thought it was a log, then perhaps a dead fox, or even a sheep swept down from a distant pasture. Only when it was almost past him did he recognise it for what it was.

He hesitated a moment, but only because he was not used to urgency. Then he ran into the bay, kicked off from the bottom and dived forward. He was a strong swimmer: a dozen strokes took him to the body. He grabbed a fistful of the man’s sodden shirt and pulled him back. The current was stronger here, hurrying him towards the open river; he let his legs sink but could not touch the bottom. The drowning man jerked under his touch, flailing and choking. He might have killed them both in his frenzy to live. Kicking furiously to stay afloat, the mudlark wrestled him down. He hooked one arm over his shoulder, another around his waist, and hauled them both back to the shore. When he had dragged his prize up onto the bank he pulled him into a sitting position, took his hands and bent him double, pumping the water out of him like a bladder.

The man-who-had-not-drowned spat, groaned, retched, then rolled over and lay heaving on the leafy ground. The mudlark left him to dry in the sun. He brought bread and honey and left them a little distance from his guest. He blew life into the fire that smouldered by his hut and warmed some milk in a bowl. By the time he returned to his guest, the food was gone and the man was sitting propped against a log. He squinted up at his saviour.

‘Thank you.’ He made an appreciative gesture with his hands. ‘If not for you…’ He trailed off.

‘What is your name?’ said the mudlark. He spoke slowly, unused to speech, his tongue searching his mouth for the sounds.

The guest smiled. ‘Aeneas.’

The name was like a stick poked into the past. Memories bubbled up through the mud: sunlight pouring through a schoolroom window, a monk in a grey cowl, an ancient book of stories.

‘Multum ille et terris iactatus et alto.’ A man tossed about on land and sea.

Aeneas sat up in surprise. He studied the mudlark, then laughed curiously. ‘What a strange fellow you are. You haunt the woods like a faun or a wild man; you swim like a mermaid and rescue travellers from their doom; and then you quote Virgil at me. Tell me, what is your name?’

The mudlark looked confused – frightened, almost. There had been so many names over the years: names called in anger, in derision, in ignorance and fear. Names given, never owned. But before them all there was:

‘Johann,’ I said.

Aeneas stayed that night in my hut. He was remarkably cheerful for a man who had almost died. By mid-afternoon he was able to stand with the aid of a staff I cut him from a willow. By dusk he had accompanied me back to the path to fetch his horse, and when night fell he built up the fire and shared the bottle of wine he had in his saddlebag. He also gave me a mirror, a silvered piece of glass set in a cast-iron frame.

‘It came from Aachen,’ he told me. ‘It has absorbed the holy radiance of the relics in the cathedral there. Take it. Perhaps some day it will bring you a blessing, as you have saved me.’

Aeneas loved to talk and delighted in company. Words poured out of him like a spring, overflowing with energy. He was particularly curious about me, though I avoided his questions. When he asked where I came from I simply pointed down the river; when he tried to discover how I had ended up dredging my miserable living from the Rhine mud, I threw another log on the fire and said nothing. Much had happened in the last ten years, but only in the way that a man falling down a well may strike the walls many times. Though each blow agonises at the time, all he remembers afterwards is hitting the bottom.

So Aeneas told me about himself. He was five years younger than me, though any observer would have looked at my face and guessed twenty. He had been born in Italy in a village near Siena; his father was a farmer of little standing, and Aeneas had rejected the fields in favour of the university.

He leaned forward so that his face shone in the firelight. ‘Did you ever feel that God made you for a purpose? I did. I knew I was destined for higher things than my father’s pastures. I studied everything I could. When the plague drove the scholars out of Siena, they could not carry all their books. I bought them for a pittance, taught myself everything they had to teach, then sold them back for five times what I had paid when the plague was over. Truly, there is nothing so profitable as knowledge.’ He chuckled at his own joke, then thought for a second. ‘Or perhaps, “Nothing profits a man like learning”? Which way sounds better?’

I shrugged. I could not help but wince at the comparison: the patrician’s heir rooting in the riverbed like a pig, and the farmer’s boy who had made more of himself. But he had not reached that part of the story.

‘At first I meant to become a doctor, or perhaps a lawyer. I have always been good with words.’ He was utterly immodest, but so sincere it did not seem boastful. ‘I tried many things – none seemed right. Then, a year ago, a man passed through our village. A cardinal, on his way to Basle.’

He squinted at me, clearly expecting some reaction or recognition.

‘You are aware there is currently a great council being held in Basle to address the wrongs of the Church?’

If I had ever known it, I had forgotten. ‘I took service with the cardinal and accompanied him.’

‘But you are not a priest?’ I asked. He did not seem like one. The first thing he had done after rescuing his horse was delve into the saddlebag for a clean shirt and hose. Even drowning in the river he had somehow managed to keep on his soft leather boots, their tops fashionably turned over to show off both their green silk lining and his calves.

He laughed. ‘Whatever God intends for me, I do not think it is holy orders. I am too much in love with the world. No – I interrupted myself. I joined this cardinal as a secretary, and he brought me to Basle. I soon found out that his riches were stored up in heaven – he did not have the money to pay me. I left his service, but I found another.’ He winked at me. ‘It was not hard. There is so much work to be done in the council that any man who can write his name is guaranteed employment.’

He rested his hand on his chin and stared into the fire, a caricature of thought.

‘You should come with me.’

Of course I resisted. But Aeneas had been right – he was clever with words. He argued with me through the night, until the fire burned low and the birds sang. He would not be refused.

The next morning, I left my hut behind and set out for Basle.