‘No, no,’ said Anton. It seemed suddenly important to him to underline his point. ‘Genetically, of course, they are identical. Dizygotic.’

‘Monozygotic, I think you mean.’

‘Indeed, indeed. Half of you in each. And half your husband. But then they’re also different, aren’t they? One wears glasses.’ He felt he made an important point and leaned back to watch it register.

‘Oh, they’re quite different once you get to know them, believe me,’ said Kitty with a laugh. ‘Do you have brothers and sisters, Herr Heideck?’

‘One brother, much older. But what I mean is that although they may be identical there is something else … And if we could discover what that was, that thing that is both familiar and elusive, the ghost beneath the skin, then I feel sure the world would be a better place.’

Kitty looked deep into his eyes and said, ‘I think you’ve put that very well.’

Anton wasn’t sure what it was that he had put so well, but felt a surging wave of warmth towards this woman for having told him so.

‘Would you like another glass of wine?’ he said. It was the only way that he could think of to register his gratitude.

Shaking her head, Kitty said, ‘The only other person who really understood, I think, was Daniel. The girls’ cousin.’

To be compared to the young man in the photograph in Martha’s consulting room … This was too great an honour, Anton felt. The man he might have killed on the battlefield … Tears were stinging his eyes. And then they were on his cheeks.

Perhaps it should be neither Johanna nor Charlotte who knocked on his door, but Kitty, this older woman of such resounding intelligence … In her arms he would find his deepest conflicts reconciled.

‘Would you excuse me for one moment?’ said Kitty, her hand on his sleeve. ‘I need to ask Martha something.’

His saviour gone, Anton took another glass of punch from the tray on a side table.

There seemed to be music, of a local kind. Some sort of hand drum was beating a rhythm and he was being shepherded to one side while the floor was cleared.

Blind Mary in a blue dress with a white flower in her hair was being manoeuvred slowly down the hall by Dr Bernthaler, while everybody stamped their feet and applauded.

Some of the people from the Emil Kraepelin building were coming in through the servants’ door behind the stairs, their anxious nurses following. Since dinner had ended, the staff had set out trestles with lemonade and beer, hot chocolate, meat pies and cakes for the new arrivals.

To begin with, they hung back against the walls, but, encouraged by Daisy and Johanna, some of them took to the dance floor. An elderly man who, it was well known, believed his thoughts to be controlled by French spies living in the grounds, had taken Martha by the hand and was now pushing her slowly and with intense concentration, like a gardener with a barrow full of fragile pots. By the fireplace, an old woman danced alone, her arms held out in front of her, as though rocking an invisible child. Cot death, thought Anton; husband lost to shellfire in Galicia. Or merely a chance arrangement of the limbs.