When he got back to Subh’s house he found his own clothes had been taken away for mending and cleaning, to be replaced by a set of clean, crisp white robes that would have suited any Moor. There was even a turban.

‘My,’ Subh said, when she met him at the gate. ‘Has your skin been oiled? You even smell civilised.’

His head full of her perfume, he could only reply, ‘Lady, I’ll take that as a compliment.’ He offered her his arm.

They walked the short distance to Seville’s royal palace, which the Moors called the al-qasr al-Mubarak, the Blessed Palace. Somehow it didn’t surprise Peter at all that Subh was held in high enough esteem by the emir to have been granted the use of rooms in his palace to meet her scholars.

They were met by one of the emir’s staff, a sleek chamberlain with a scalp shaved smooth and polished oak-brown. He led them on a gentle walk through the rooms of the palace, which led from one to the other in the indirect Moorish style, filled with water-reflected light from patios and gardens. In some of the rooms they glimpsed people at leisure, wives and princes perhaps, and palace staff who worked on the business of running the emirate.

‘I’m impressed you organised this so quickly,’ he said.

‘We may need to be hasty, if the rumours I’ve been hearing about the Christians’ plans are true. We have a few years at best before Seville is besieged the way Cordoba was. So we must get on with it. But tell me - do you despair of the quality of our scholars in these latter days? After all the great age of the caliphate is long gone.’

‘Not at all. I have studied Ibn Rushd, for instance, whom we know as Averroes. An astronomer, physician, philosopher, who is generally believed to have produced the best commentary on Aristotle since antiquity, and stirred up some trouble with it. Ibn Bajjah, a teacher of medicine, and tutor of Ibn Rushd. Al-Jayyani, who wrote commentaries on Euclid. Al-Maghribi, famous for trigonometry. Al-Zarqali, the foremost astronomer—’

‘Enough. You have convinced me. You know,’ she mused, ‘these scholars are heroes to you. But my son’s heroes are men like Tariq and Saladin. Warriors. Makes you think.’

‘I’ll tell you something else about Muslim learning. Many Arabic words have no Latin equivalents, because the scholarship is so much more advanced. So when the work of Ibn Rushd, for instance, is translated into Latin, the Arabic words are copied over as they are. Alkali. Camphor. Borax. Elixir. Algebra. Azure. Zenith. Nadir. Zero. Cipher—’

‘Enough of your lists, boy!’

‘Do you think that people in England and Germany will end up speaking Arabic without even knowing it?’

‘Now that,’ she said, ‘is a delicious thought.’