Then they came to a meadow in the sky. It was a high, broad plain, suspended between two looming mountains. A meadow, complete with thick grass and dancing wild flowers. There were sheep up here, fat-looking beasts who fled at the party’s approach. All of this lay under a brilliant blue sky, the green of the grass and the sheep’s pale wool vivid. It was like a dream, Avatak thought; it seemed impossible this could be real, could be here. The horses tore eagerly at the rich grass. Even the mule could barely conceal its pleasure at the lush pasture.

Jamil and Uzzia both knew this place. ‘Here we will stop,’ Jamil said firmly. ‘For two nights, three, while the horses feed, and we rest.’

Avatak could see the wisdom of it. By now the party was much reduced: just the four travellers of Pyxeas’ party, and two other traders, Arabs who had kept to themselves from the beginning of the trek, and six local bearers and guides. They were all exhausted; they all needed time to get used to the air.

Still, Avatak was surprised that Pyxeas agreed to the stop readily. ‘But the timing is good,’ the scholar said. ‘Tonight the eclipse is due. Make sure you have the oracle ready, boy.’

Uzzia, unpacking her own bundles, glanced over. ‘What eclipse?’

Jamil grunted. ‘What is an “eclipse”?’

‘An eclipse is a shadow play. When the world falls into the shadow of the moon, and the sun’s light is blocked out . . . or, as tonight, when the moon enters the shadow of the earth, and turns the colour of blood.’ Pyxeas had been in good spirits for days, buoyed up by the thin air. Now it was almost as if he was drunk. ‘A world of shadow, a moon of blood!’ He repeated the words in other, fragmentary languages: Uzzia’s Hatti, Jamil’s Arabic, even in broken phrases in the harsh local argot.

The men working at the horses glanced across at him, and then up at the sunlit sky, uneasy. Jamil, watching, shook his head, muttering about folk who had so much cleverness it drove the wisdom out of their heads, and went back to unpacking his own tent.

The sun set and the moon rose, full and handsome. Sitting cross-legged with a blanket over his shoulders Pyxeas set the oracle on the ground before him, working its dials, muttering to himself. Meanwhile he had Avatak set up the hourglass and record the hours since sunset.