‘That the world is a dangerous place. The Romans called the Ocean Sea the Mare Ignotum, the unknown, and not for nothing. They say that to the west is a Sea of Doom, a place of vast whirlpools that can crush a ship like a fly in a child’s fist. If you go south towards the equator you sail into the Torrid Zone, where the sun’s heat turns you black before the flesh boils off your bones. And the world is not a sphere, as the ancients believed, but a sort of pear-shape, with a great extension to the extreme east where the earthly paradise resides.’ He felt uncomfortable, as Abdul listened to this in cold silence. ‘This is what has been said by mariners to me.’

‘All right,’ Abdul said. ‘But what mariners? Europeans, that’s who, who have barely ventured out of the puddle that is the Mediterranean. But the Chinese have gone much further, and learned much more . . .’

And he spoke of his time on the treasure ships.

‘You should have seen them, cousin. They were not like our little ships at all. Like floating cities, they were, with a great square bow at the front, topped by serpents’ eyes. Nine masts bore huge red silk sails. The ships were built in compartments, so they could not be sunk. They had holds full of preserved food, and immense tanks of fresh water, and they grew soya beans on board, and they kept otters in their holds to catch fish - they could stay at sea for months! And the officers enjoyed banquets and dances, and the company of courtesans.

‘It’s all gone now. There was upheaval at court, a fire in the Forbidden City, a lot of bad omens - the eunuch admirals were retired, the ships broken up. The mandarins at court adhere to the principles of tao - order, stability, harmony of all things. That sort of thinking doesn’t sit well with the exploration of the unknown. I suppose in the end the Chinese decided China is world enough for them.

‘But in the heyday of these tremendous ships, only a few decades ago, the Chinese ventured far over the oceans - around India, as far as the coast of Africa, and to the south-east, where they discovered huge masses of land and strange peoples unknown to Europeans.

‘Listen to me. I once met a man who had worked in the Forbidden City. In a zoo there, he said, the eunuch explorers had brought back specimens from a dry southern land. There were strange skinny people with black skin and flat noses and curly hair. There were trees that kept their leaves and shed their bark. There were huge creatures with faces like a deer’s and back legs like huge levers, that carried their young around in a flap of skin on their belly . . .’

Harry smiled. ‘I too have heard such tavern tales.’