They were staying in a hilltop town a short train journey away from the big city. The hotel was inexpensive, clean and discreet. The view from the window was of the plain below, where the spring narcissi massed, and a milky-looking mountain in the distance.

Lying open on the floor beside the bed was her notebook, containing her botanical painting of the narcissi. On the opposite page was a transverse section of its seed head. She had taken her time to select the best specimen and dissected it with the sharpened knife she kept in her bag.

To keep off dangerous subjects – what had taken place between them, the future – they discussed the two paintings they had seen earlier in the morning, sightseeing.

The town’s ducal palazzo was run-down and shorn of artefacts. Pacing behind the guide, who was so desperate that he resorted to pointing out the guttering, they had escaped to its museum, which had nothing in it except for the ducal chair and an exquisite miniature painting of Bathsheba bathing.

The label stated that it had been discovered during restoration work in the palazzo and later authenticated as an original from a book of hours commissioned by the then duchess in 1489 and painted by Pucelle fils, a celebrated master.

Its subject was Bathsheba bathing in a pool with a fountain playing. It showed her with milky-white, unblemished skin and a slender waist above broadly curving hips and exposed pudendum – a glorious, jewel-like homage to lust. And yet, by placing her in the water, with King David gazing down on her from a distant palace, the painter was cleverly keeping her at one remove. Beware of sensuality was the message.

She had studied it for a long time.

Close by, in the church on the piazza, was another medieval painting, this time of the Annunciation. Here, the Virgin sat peacefully in the garden, wearing a cloak of the most intense blue. A rabbit and a mouse sheltered under her skirts. An archangel was winging down, bearing a lily.

She had stood in front of it, and the colour of the Virgin’s cloak had shimmered, and grown deeper, burning into her vision: the deep, deep blue of peace and certainty.

Now she stirred in his arms.

‘All right?’ His breath fell on her cheek.

‘The blue makes the heart sing.’ She was beginning to feel sleepy. ‘It’s remarkable.’

‘Made from powdered lapis lazuli. Probably.’

‘Is it?’ She looked up at his face. Since their time together was always short, she liked to take an inventory of every expression. ‘How did they convert it into paint?’

‘Water and gum Arabic. But it was only applied at the last minute.’ He, too, was drowsy. ‘It would be used for her cloak, and she would be wearing it at every stage of her life as a mother. Annunciation, birth, flight into Egypt, taking Christ to the temple …