Julius took the night train back from Paris. He slept fitfully, a thin sleep threaded with whistles and the jolting clatter of wheels. It was still dark when he rose. In the dining car a yawning waiter brought him a cup of weak coffee. With its teak panelling and glass- shaded lamps, the diner was all that remained of the elegant Nord- Express which had run this route before the war. Julius stared out of the window. There was no moon. The passing telegraph poles sliced the blackness into squares.

He supposed he should feel anger, grief even, but all he could summon was the weariness of defeat. His marriage was over and the end, like so much about Luisa, was both tawdry and unutter ably banal. The pair of them writhing and grunting in her tumbled bed, their frozen horror as he switched on the light. He gave them one minute to get out of his house before he called the police. Frau Lang covered her face with her apron as they fled down the stairs, their clothes bundled in their arms. He should have done the same. I worship the nude like a god, Rodin once said, but there was nothing godlike about their nakedness, their shrivelled cocks, the skinny white shanks of their legs.

And later Luisa, oblivious Luisa in the bottle-littered drawing room, her make- up smeared and her dress falling off one shoulder, her arm around Lehmbruck’s Kneeling Woman, a silver straw between her fingers like a cigarette. Her contemptuous smirk as she leaned down, eyes glittering, and snorted cocaine from the sculpture’s cast stone thigh. When he told her he wanted a divorce she laughed, shrill and sharp, like glass breaking.

‘I’ll drink to that,’ she said and, hoisting a champagne bottle by the neck, she put it to her lips. The wine ran out of her mouth and over her chin.

The train slowed. Above the dark curve of the hills a grey dawn was breaking. Quicksilver balls of rain rolled diagonally down the window. Julius closed his eyes, his fingertips kneading the back of his neck. Though it troubled him to admit it, he was as much to blame as she was. Such a weakness you have for beautiful things, his old friend Bruno said drily when Julius first introduced them, and Julius only laughed. He was fifty- three, recently demobbed and dizzy with desire. Luisa was twenty- four. In the bleak, broken down months after the armistice her loveliness was a kind of miracle. He could not get enough of her. In her arms the past grew hazy, shedding its horrors, and the future was ravishing and new. He thought she would heal him, that he could wash himself clean in the clear, cool stream of her. By the time he understood that he was wrong, that her exquisite face masked a crude, incurious mind and what he had taken for innocence was nothing but ignorance and lack of imagination, she was already his wife.

Five years, three of them more or less wretched. They were neither of them what the other had imagined them to be. Their arguments, once fiery, grew bitter, hard with disappointment. There were no more passionate reconciliations, only silences, brief distrustful breaks in the bombardment. Like opposing armies they dug into their positions. Julius returned to his bachelor habits, 5 burying himself in his work. Luisa shopped and danced and shrieked till dawn.

He was ashamed, that was the truth. He had built his reputation, his whole life, on his ability to see, not only with his eyes but with his heart. In The Making of Modern Art he had railed against an establishment blinded by the seductions of technical virtuosity, urging them to seek instead the heroic struggle that was the soul of great art, and yet, confronted with Luisa, he had made all the same mistakes. He had succumbed to the surface of her, mistaken her physical perfection for a purity of spirit, for something transformative and true.

A couple came into the dining car. The woman was short and dark with sleepy Modigliani eyes. She smiled at Julius and wished him a good morning, her German heavily accented with Russian. Julius nodded in return. He would do the decent thing. Since the Kaiser, with characteristic compassion, had deemed insurmountable aversion insufficient grounds for divorce, it was necessary for one side or the other to take the blame. Adultery was cleanest. In cases of proven adultery, divorce was granted automatically. The newspapers might still take an interest, but there was none of the public scandal that dogged a contested hearing.

He would talk to Böhm this afternoon, have him make the necessary arrangements. In Berlin there were plenty of women who would pretend to have fucked you for a fee. He would pay for his principles, of course. Only guilty husbands paid alimony. And while a part of him raged against financing any more of Luisa’s extravagances – for the bourgeois daughter of a money- doesn’t- grow- on- trees bank manager, she had always displayed a staggeringly can- do attitude to prodigality – a larger part was glad. An honourable man paid for his mistakes. He took his punishment, however harsh. There was a kind of purification in it, a humility that was almost grace. And it was not as if he did not have the money. The van Gogh book had proved a runaway bestseller, not only in Germany but in France and Britain too. America beckoned. The royalties would have left him comfortably off even without the recent collapse in the value of the mark. With exchange rates as they were he could afford to be generous. Besides, there was the child to think of. People would gossip, they always did, but he would not have anyone say he had mistreated the mother of his son.